具体实施方式：
[0024]Where ever possible the same reference numbers are used throughout the drawing(s) and accompanying written description to refer to the same or like parts. The figures are not necessarily to scale and certain features and certain views of the figures can be shown exaggerated in scale or in schematic for clarity and/or conciseness. Additionally, several examples have been described throughout this specification. Any features from any example can be included with, a replacement for, or otherwise combined with other features from other examples.
DETAILED DESCRIPTION
[0025]Certain examples are shown in the identified figures and disclosed in detail herein. Although the following discloses example methods and apparatus, it should be noted that such methods and apparatus are merely illustrative and should not be considered as limiting the scope of this disclosure.
[0026]As used herein, directional terms, such as “upper,”“lower,”“top,”“bottom,”“front,”“back,”“leading,”“trailing,”“left,”“right,” etc. are used with reference to the orientation of the figures being described. Because components of various examples disclosed herein can be positioned in a number of different orientations, the directional terminology is used for illustrative purposes and is not intended to be limiting.
[0027]Additive manufacturing processes can be used to manufacture parts having complex geometries. However, parts manufactured via additive printing processes are often limited to a small section of materials (e.g., 3D printable materials). For example, a small portion of polymer materials in the manufacturing industry can be used as 3D printing material(s). Thus, material availability has been a significant limitation for 3D printing processes compared to other manufacturing processes. Additionally, additive manufacturing processes can be expensive and/or can be time consuming process. In some instances, 3D printed parts can have relatively weak strength (e.g., mechanical strength, stress or strain characteristic(s)) compared to, for example, machined parts or molded parts. Other manufacturing processes employing molds are compatible with many different types of materials (e.g., thermoplastic and thermosetting polymer materials, etc.). However, such known manufacturing processes employing molds are limited to the production of simple geometries because complex parts cannot be separated from the molds.
[0028]Examples disclosed herein provide methods for manufacturing molds having complex geometries via additive manufacturing processes (e.g., 3D printed molds). For example, 3D printing techniques or processes are considered additive processes because the 3D printing processes involve the application of successive layers of material. Example 3D printing processes involve curing or fusing of a building material, which can be accomplished using heat-assisted extrusion, melting, or sintering, digital light projection technology, etc. For example, 3D printed objects can be printed using, for example, a multi-jet fusion (MJF) process. MJF is a powder-based technology. A powder bed is heated uniformly at the outset. A fusing agent is jetted where particles need to be selectively molten, and a detailing agent is jetted around the contours to improve part resolution. While lamps pass over a surface of the powder bed, the jetted material captures the heat and helps distribute the heat evenly.
[0029]In some examples disclosed herein, 3D printed molds can be manufactured via MJF technology. The 3D printed molds are then employed in other manufacturing processes such as, for example, injection molding, casting etc., to manufacture parts using non-3D printable materials. After formation of the 3D printed mold, a moldable material can be provided in a cavity of the 3D printed mold. As used herein, a “moldable material” is any material such as, for example, a liquid, a powder, clay, etc., that becomes liquid or malleable when heated (e.g., to a temperature of 150 degrees Fahrenheit (° F.)) and solidifies when cooled (e.g., to room temperature). For example, the moldable material can be, for example, a liquid or a powder, a polymer, a molten material, a liquid polymer, a polymer mixed with metal or ceramics, a low-temperature metal, and/or any other suitable material(s). The moldable material can then be treated (e.g., cooled, cured, etc.) for solidification. After solidification of the molded material, the mold can be separated (e.g., destroyed and removed) from the molded part. Thus, the example 3D printed molds disclosed herein can be single use molds that can be broken down and removed from a molded part after formation of the molded part.
[0030]In 3D printing processes, full solidification of materials has always been desired for highest mechanical strength possible. For example, in thermal powder bed-based 3D printing processes, such as MJF for plastic materials, process parameters are optimized to avoid under-fused powder to form fully dense parts (e.g., 0% to 1% porosity). As used herein, “porosity” means a measure of a void (i.e. “empty”) spaces in a material. In some examples, porosity is determined as a fraction of a volume of voids over a total volume, or as a ratio of a volume of interstices of a material to a volume of its mass. A degree of fusion in powder bed-based 3D printing processes affects resulting material properties such as, for example, Young's modulus, ultimate strain and stress, etc. Therefore, printing a 3D part with an under-fused polymer powder can present mechanical strength properties different from mechanical strength properties of a fully-fused polymer powder.
[0031]To enable separation of the mold from the molded part, example molds disclosed herein can be formed with weakened area or breakaway features (e.g., under-fused polymer powder) during the 3D printing process. To form the breakaway features, a level of fusion of a part is varied during 3D printing process. As used herein, a level of fusion refers to controlling an amount of heat to be received by a build material to affect or control an amount of melt of particles to be selectively molten and, thus, vary a porosity of a part (e.g., a 3D printed mold). For example, to form the breakaway features and/or vary a level of fusion, a level of a fusing agent or binding or bonding agent for 3D binder jetting is varied during the printing process, an amount of heat applied to different regions of the 3D part is varied to vary (e.g., increase or decrease) a level of molten of particles of the different regions, a cooling agent may be provided to control (e.g., lower) a temperature of a first region relative to a second region to reduce the number of particles that become molten. For example, forming 3D printed molds disclosed herein with under-fused powder decreases a mechanical strength of the under-fused area compared to a mechanical strength of a fully-fused powder.
[0032]In other words, controlling a fusion level can alter mechanical strength characteristics of the molded part. For example, first portions of the 3D printed mold can have a first strength characteristic and second portions of the 3D printed mold can have a second strength characteristic different than (e.g., less than) the first strength characteristic. Therefore, different portions of the mold can be weakly connected to enable removal of the 3D printed mold from a molded part. As a result, the 3D printed mold has sufficient strength to maintain its shape during a molding process but can be broken down after formation of the molded part.
[0033]To control fusion levels or characteristics, the examples disclosed herein control a temperature of a first portion or region (e.g., of a layer) of a 3D printed part relative to a temperature of a second portion or region (e.g., of a layer) of the 3D printed part. To vary the porosity and/or a level a fusion, the examples disclosed herein vary a fusing agent (e.g., MJF process), a detailing agent (e.g., a cooling agent), an energy level (e.g. SLS process), a binder agent (e.g., 3D binder jetting), etc.
[0034]For example, to control fusion levels or characteristics and/or vary a porosity during an MJF 3D printing process, example disclosed herein employ (1) a contone level-controlled approach or (2) a heat transfer-controlled approach. In the contone level-controlled approach, fusing agents are applied to the under-fused regions at lower contone levels than that of the fully fused regions. The desired fusing degree of the under-fused region can be achieved by the corresponding contone level. In the heat-transfer-controlled approach, no fusing agent is applied to the under-fused region. Instead, a region is solidified by the heat (e.g., thermal bleed) from the fully fused regions adjacent the under-fused region. Different portions of the mold can therefore be weakly connected.
[0035]To vary porosity and/or fusing level characteristics during a selective laser sintering (SLS) process, examples disclosed vary an energy provided to a build material during the SLS process. For example, an SLS process employs a laser that provides energy sufficient to cause particles of a build material to fuse together and form a solid structure. Thus, to vary the porosity, a first energy level (e.g., a first amount of heat) can be provided to the first region (e.g., of a first layer) of a 3D printed mold and a second energy level (e.g., a second amount of heat) can be provided to the second region (e.g., the first layer) of the 3D printed mold. In some examples, the first energy level is provided by a first laser and the second energy level is provided by a second laser.
[0036]Example disclosed herein can be employed with 3D binder jetting processes. For example, 3D binder jetting is an additive manufacturing process that forms 3D printed parts or molds additively with a binding agent. In some examples, the 3D binder jetting process uses a liquid binding agent deposited on a metal powder material, layer by layer, according to a 3D model. In some such examples, a porosity of (e.g., a first layer) of a 3D printed mold can be varied by varying at least one of the binder agent or an energy applied to a build material and the binder agent.
[0037]In some examples, the example methods disclosed herein can employ a detailing agent (e.g., a cooling agent) to vary a porosity of a 3D printed mold. The detailing agent maintains a temperature of a second portion of a build material cooler than a temperature of a first portion of a build material during a printing process to reduce or prevent the effects of thermal bleed between the first portion and the second portion and, thereby, vary a porosity between the first and second portions. Thus, although the example disclosed herein are discussed in connection with MJF process, the examples can be implemented with SLS processes, 3D binder jetting processes, and/or any other additive manufacturing process(es).
[0038]Further, the variation of porosity between a first region and a second region (e.g., of a layer) of a 3D molded part disclosed herein defines a breakaway feature. Thus, the example 3D printed molds disclosed herein do not include any inserts or structures (e.g., metal inserts) to define or enable the breakaway feature. The breakaway features are enabled by a variation of the porosity or fusion level of the first region and the second that is controlled during manufacturing or printing (e.g., an MJF printing process, an SLS printing process, a 3D binder jetting process, etc.) of the 3D printed mold 102. Turning more specifically to the illustrated examples, FIG. 1 depicts an example workstation 100 that can be employed to manufacture a 3D printed mold 102 in accordance with teachings of this disclosure. The workstation 100 of the illustrated example employs MJF technology to fabricate the 3D printed mold 102. The 3D printed mold 102 may be formed through an MJF process where powder particles are fused together through application of a fusing agent and heat. In some examples, the workstation 100 can be a Jet Fusion 4200 series 3D printer manufactured by HP, Inc. The 3D printed mold 102 can be composed of material(s) including, for example, polymers or a mixture of polymer and metal/ceramic material(s) including, but not limited to, nylons (e.g., nylon 12, nylon 11, nylon 6, etc.), polypropylenes, polyethylene, thermoplastic polyurethane and/or any other semi-crystalline thermoplastic(s) and/or polymer material(s).
[0039]The workstation 100 includes an example controller 104 and an example printer 106 (e.g., a 3D printer). The controller 104 may be a computing device, a semiconductor-based microprocessor, a central processing unit (CPU), an application specific integrated circuit (ASIC), and/or other hardware processing device. The controller 104 can be communicatively coupled to an example computing device 110 (e.g., a desktop, a server, etc.) via an example network 108 (e.g., a wireless network, a wired network, etc.). For example, the computing device 110 may be a computer that sends instructions to the controller 104 to print or produce the 3D printed mold 102. While an example network topology is shown in FIG. 1, any appropriate network topology may be implemented.
[0040]The printer 106 of the illustrated example includes an example build material dispenser 112, an example support bed 114, an example fusing agent dispenser 116, an example detailing agent dispenser 118, and an example energy source 120. The build material dispenser 112, the fusing agent dispenser 116, and/or the detailing agent dispenser 118 can be inkjet cartridge(s) or print heads that eject material(s) during a printing process. The energy source 120 can be, for example, infrared light, ultraviolet light, a heat lamp, a heating element, and/or can be any other source that produces heat.
[0041]The printer 106 of the illustrated example produces the 3D printed mold 102 with an example first area or first region 122 and an example second area or second region 124 different than the first region 122. The 3D printed mold includes a plurality of layers. Thus, the first region of a first layer of the 3D printed mold 102 aligns with a first region (e.g., a third region) of the second layer and the second region of the first layer aligns with a second region (e.g., a fourth region) of the second layer. In the examples disclosed herein, one layer or multiple layers can define the first region 122 and/or the second region 124.
[0042]The first region 122 of the illustrated example is formed with a first porosity, and the second region 124 is formed with a second porosity different than the first region 122. In particular, the first porosity may be less than the second porosity. In some examples, the first porosity is between approximately 0% and 5%. In some examples, the second porosity is between approximately 10% and 90% greater than the first porosity. In some examples, the second porosity can between approximately 30% and 80% greater than the first porosity. Thus, the first region 122 has a greater density than the second region 124.
[0043]As a result of the varying porosities, the first region 122 has a first mechanical strength characteristic (e.g., ultimate strain and stress, impact resistance, etc.) that is different than (e.g., greater than) a second mechanical strength characteristic (e.g., ultimate strain and stress, Impact resistance) of the second region 124. For example, when the 3D printed mold 102 is composed of nylon 12, the first region 122 (e.g., a fully-fused region) can have an ultimate stress characteristic of between approximately 25 megapascal (MPa) and 80 megapascal (MPa) (e.g., 60 MPa), and the second region 124 (e.g., a partially-fused region) can have an ultimate stress characteristic of between approximately 5 megapascal (MPa) and 20 megapascal (MPa) (e.g., 10 MPa). In some examples, when the 3D printed mold 102 is composed of notched nylon 12, the first region 122 can have an Izod Impact characteristic of between approximately 2 KJ/m2 and 10 KJ/m2 (e.g., 3.5 KJ/m2), and the second region 124 (e.g., a partially-fused region) can have an Izod Impact characteristic of between approximately 0.1 KJ/m2 and 3 KJ/m2 (e.g., 1 KJ/m2). To this end, the second region 124 provides a breakaway feature that enables or facilities separation of the first region 122 into multiple segments or structures. Thus, a force imparted to the second region 124 can cause the second region 124 to break, while the first region 122 can withstand the same amount of force. To provide the breakaway feature, the controller 104 of the illustrated example causes the printer 106 to vary a porosity of a 3D molded part during the printing operation to provide at least the first region 122 having a first porosity and the second region 124 having a second porosity that is greater than the first porosity. To achieve varying porosity between the first region and the second region, the examples disclosed herein control a temperature or heat absorption of a build material during printing of the first and second regions. To control the temperature of a build material of the first and second regions during printing process and vary the porosity of the 3D printed mold 102, examples disclosed herein include controlling at least one of: (1) a contone level of a fusing agent; or (2) a heat transfer during the printing process. The varying degree of porosity between the first region 122 and the second region 124 is controlled by a level of fusion between the first region 122 and the second region 124. For example, the first region 120 has a fully-fused area (e.g., a small porosity of, for example, between 0% and 5%), and the second region 124 has a partially or under-fused area (e.g., a large porosity of, for example, between 10% and 90%). This level of fusion variation is controlled by controlling a temperature of the first region 122 relative to the second region 124. In other words, the fusing agent can be employed to control a temperature of the second region 124 relative to the first region 122.
[0044]After formation of the 3D printed mold 102, the 3D printed mold 102 can be used to form a molded part 126 via other molding (e.g., casting) manufacturing processes. After the molded part 126 solidifies in the 3D printed mold 102, the 3D printed mold 102 is removed from the molded part 126 by separating the 3D printed mold 102 into multiple segments or pieces via the second region 124. The segments of the 3D printed mold 102 are removed from the molded part 126.
[0045]The examples disclosed herein are not limited to MJF process. For example, the workstation 100 can be configured to implement any other suitable additive manufacturing processes. In some examples, the examples disclosed herein can employ a detailing agent process, a selective laser sintering (SLS), or a 3D binder jetting process to vary a porosity between the first region 122 and the second region 124 of the 3D printed mold 102.
[0046]To implement a detailing agent process, the workstation 100 of FIG. 1 can be configured to dispense a detailing agent (e.g., water, a cooling agent, etc.) to control a temperature of the first region 122 and the second region 124. For example, the controller 104 can cause a detailing agent dispenser to dispense a detailing agent (e.g., a liquid, water, etc.) on a build material corresponding to the second region 124. Such application of the detailing agent can occur without use of a fusing agent on the build material associated with the second region 124. In some examples, a combination of the fusing agent and the detailing agent can be used on the second region 124 to increase a porosity of the second region 124. During a fusing process (e.g., of a layer) of the 3D printed mold 102 that occurs during a printing process, the fusing agent disposed on the build material associated with the first region 122 absorbs a greater amount of heat than a portion of the build material that includes the detailing agent associated with the second region 124. In this manner, the first region 122 heats to a temperature that is greater than the second region 124 to cause the first region 122 to become molten and fuse together with a less porosity than the second region 124. Additionally, the detailing agent provided on the build material corresponding to the second region 124 maintains a temperature of the build material cooler than a temperature of the build material corresponding to the first region 122 to reduce or prevent the effects of thermal bleed from the heat of the first region 122 to the second region 124 due to the temperature of the first region 122. In other words, the detailing agent can be employed to control a temperature of the second region 124 relative to the first region 122.
[0047]Alternatively, in some examples, the workstation 100 can be configured to implement a selective laser sintering (SLS) apparatus or process. In some such examples, the energy source 120 can be a laser that applies energy to a build material provided by the build material dispenser 112. To vary a porosity of a 3D printed mold between a first region (e.g., of a first layer of the 3D printed mold) and a second region (e.g., of the first layer of the 3D printed mold), the energy source 120 varies an amount of energy provided to (e.g., a layer of) the 3D printed mold. For example, the controller 104 can command the energy source 120 to provide a first amount of energy to the first region of the 3D printed mold and a second amount of energy different than the first to a second region of the 3D printed mold. The varying amount of energy causes particles of a build material to fuse with different porosities. For example, the first region can be formed with a first porosity (e.g., 0 to 5%) and the second region can be formed with a second porosity (e.g., 10% to 90%) different than the first porosity. In some such examples, the workstation 100 does not include the fusing agent dispenser 116 and the detailing agent dispenser 118.
[0048]In some examples, the workstation 100 can be configured to implement a 3D binder jetting process. For example, the printer 106 can include a binder agent dispenser instead of the fusing agent dispenser 116 and the detailing agent dispenser 118. To vary a porosity of a 3D printed mold, the printer 106 can vary at least one of a binder agent provided to a build material or an amount of energy provided to the binder agent and the build material. For example, to vary the porosity between first and second regions, the controller 104 can cause the binder dispenser to dispense a first amount of binder agent on a first region (e.g., of a first layer) of the 3D printed mold and a second amount of binder agent on a second region (e.g., of the first layer) of the 3D printed mold. In some examples, to vary the porosity, the controller 104 causes the energy source 120 to provide a first amount of energy or first energy level to a first region (e.g., of a first layer) of the 3D printed mold and a second amount of energy or second energy level to a second region (e.g., a second layer) of the 3D printed mold. In some examples, a porosity between a first region and a second region of the 3D printed mold can be varied by varying the binder agent and the energy applied to the binder agent and a build material.
[0049]Further, the example breakaway feature is defined based on the varying porosity between the first and second regions 122, 124. Thus, the example 3D printed mold 102 does not include any inserts or structures (e.g., metal inserts) to define or enable the breakaway feature. The breakaway feature is enabled by a variation of the porosity or fusion level of the first region 122 and the second 124 that is controlled during printing (e.g., an MJF printing process, an SLS printing process, a 3D binder jetting process, etc.) of the 3D printed mold 102.
[0050]While an example manner of implementing the workstation 100 is illustrated in FIG. 1, any or some the elements, processes, and/or devices illustrated in FIG. 1 may be combined, divided, re-arranged, omitted, eliminated, and/or implemented in any other way. Further, the example controller 104, the example printer 106, the example build material dispenser 112, the example support bed 114, the example fusing agent dispenser 116, the example detailing agent dispenser 118, the example energy source 120 and/or, more generally, the example workstation 100 of FIG. 1 may be implemented by hardware or machine readable instructions including, for example, software or firmware, and/or implemented by any combination of hardware, software and/or firmware. Thus, for example, any of the example controller 104, the example printer 106, the example build material dispenser 112, the example support bed 114, the example fusing agent dispenser 116, the example detailing agent dispenser 118, the example energy source 120 and/or, more generally, the example workstation 100 of FIG. 1 could be implemented by analog or digital circuit(s), logic circuits, programmable processor(s), programmable controller(s), graphics processing unit(s) (GPU(s)), digital signal processor(s) (DSP(s)), application specific integrated circuit(s) (ASIC(s)), programmable logic device(s) (PLD(s)), and/or field programmable logic device(s) (FPLD(s)). When reading any of the apparatus or system claims of this patent to cover an implementation of purely machine readable instructions, at least one of the example controller 104, the example printer 106, the example build material dispenser 112, the example support bed 114, the example fusing agent dispenser 116, the example detailing agent dispenser 118, the example energy source 120, and/or, more generally, the example workstation 100 of FIG. 1 is/are hereby expressly defined to include a non-transitory computer readable storage device or storage disk such as a memory, a digital versatile disk (DVD), a compact disk (CD), a Blu-ray disk, etc. including the software and/or firmware (e.g., machine readable instructions). Further still, the example workstation 100 of FIG. 1 may include other element(s), process(es), and/or device(s) in addition to, or instead of, those illustrated in FIG. 1, and/or may include more than one of any or all of the illustrated elements, processes, and devices. As used herein, the phrase “in communication,” including variations thereof, encompasses direct communication and/or indirect communication through intermediary component(s), and does not require direct physical (e.g., wired) communication and/or constant communication, but rather additionally includes selective communication at periodic intervals, scheduled intervals, aperiodic intervals, and/or one-time events.
[0051]FIG. 2 is a schematic illustration of an example additive manufacturing process 200 (e.g., an MJF process) for forming the 3D printed mold 102 via the workstation 100 of FIG. 1. To form the 3D printed mold 102, the controller 104 receives instructions (e.g., via the computing device 110 and/or the network 108) to fabricate the 3D printed mold 102. For example, the controller 104 can receive instructions representative of a desired pattern to create or generate the 3D printed mold 102. The controller 104 of the illustrated example causes the build material dispenser 112, the fusing agent dispenser 116, the detailing agent dispenser 118, and the energy source 120 to move along a pre-determined pattern relative to the support bed 114 to generate or build the 3D printed mold 102. For example, the instructions may be provided via a digital file formed using computer aided design (CAD) programming.
[0052]To produce the 3D printed mold 102, the controller 104 causes the build material dispenser 112 to dispense a build material 202 on the support bed 114 (e.g., a powder bed-based 3D printing processes). The build material 202 is a powder based material (e.g., nylon powder). In some examples, the build material dispenser 112 dispenses or deposits the build material uniformly across (e.g., an entire) working area of the support bed 114. To facilitate fusion (e.g., solidification) of the build material 202, the fusing agent dispenser 116 dispenses a fusing agent 204 (e.g., an agent) on the build material 202. Specifically, the fusing agent 204 is jetted on the build material 202 at specific locations or regions where particles of the build material 202 are to be selectively molten or fused together. To generate a pattern corresponding to the 3D printed mold 102, the controller 104 of the illustrated example controls dispensing the fusing agent 204 at specific locations relative to the build material 202 via the fusing agent dispenser 116. In some examples, a detailing agent 206 is jetted (e.g., via the detailing agent dispenser 118) around the contours of fused portions of the 3D printed mold 102 to improve part resolution. Typically, the detailing agent 206 is provided at peripheral or terminating edge 208 of the 3D printed mold 102. In contrast to the fusing agent 204, the detailing agent 206 reduces or prevents fusion or solidification of the build material 202.
[0053]To solidify or fuse the build material 202 to a structural component 210 (e.g., a solid structure), the controller 104 causes the energy source 120 (e.g., infrared light) to heat (e.g., pass over) the build material 202. As the energy source provides heat to the build material 202, the fusing agent 204 absorbs the heat and distributes the heat evenly to portions of the build material 202 that includes the fusing agent 204. Thus, the fusing agent 204 enhances fusion or solidification of the build material 202. The detailing agent 206, on the contrary, reflects heat from the energy source 120 and does not allow the build material 202 to solidify or fuse, thereby facilitating removal of the 3D printed mold 102 from the support bed 114.
[0054]After a first layer 212 of the 3D printed mold 102 is formed, a second layer 214 of the 3D printed mold 102 is formed. For example, after formation of the first layer 212, the controller 104 causes the build material dispenser 112 to deposit the build material 202 on the first layer 212 and causes the fusing agent dispenser 116 to dispense the fusing agent 204 on select regions of the build material 202 of the second layer 214 that is to molten or solidify. The energy source 120 applies energy to the build material 202, and the build material 202 solidifies at locations that includes the fusing agent 204 to form the second layer 214 of the 3D printed mold 102. The process repeats to form a plurality of layers until formation of the 3D printed mold 102 is completed.
[0055]FIG. 3 is a plan view of the first layer 212 of the 3D printed mold 102 of FIGS. 1 and 2. The first layer 212 of the 3D printed mold 102 of the illustrated example includes the first region 122 and the second region 124. Specifically, the first region 122 of the illustrated example includes a plurality of first regions 302 and the second region 124 of the illustrated example includes a plurality of second regions 304. The first regions 302 of the illustrated example are produced with the first porosity and the second regions 304 are produced with the second porosity different than the first porosity. Additionally, the controller 104 causes the second region 124 of the first layer 212 to align with a second region of the second layer 214 during the printing operation of the 3D printed mold 102. The second regions 304 of the illustrated example enable separation of the first regions 302 into multiple segments (e.g., four segments). To this end, the second regions 304 define breakaway features 306 that enable the first regions 302 to separate (e.g., break off) into multiple segments or structures 308.
[0056]FIG. 4 is schematic illustration of an example layer 402 (e.g., the first layer 212 of FIG. 2) of the 3D printed mold 102 formed with a varying porosity between the first region 122 and the second region 124 via an example contone-level control approach 400. To vary a porosity between the first region 122 and the second region 124 of the 3D printed mold 102, the controller 104 controls a contone level of the fusing agent 204 deposited or dispensed (e.g., jetted) on the build material 202 via the fusing agent dispenser 116. For example, the first region 122 receives a first amount 404 of the fusing agent 204 and the second region 124 receives a second amount 406 the fusing agent 204. Specifically, in this example, the first amount 404 is greater than the second amount 406. In some