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You can use any simple shape (sphere, rectangular prism, block, etc.) but for the purposes of this section, we will be using a sphere (sphere.SLDPRT). (Please see insert link for tutorial page hereSolidWorks Basics for instructions on how to create these shapes.)
To create a mold from the intersection between two (or more) shapes, you will have to have the shape (see above) be using the shape, in this tutorial, a sphere, and create a separate part that a New Part that is a solid block. Notably, this block should be larger than the cross-section of the part in which a mold will be made from it. Choose the Front Plane and use the 
option to draw a rectangle from the center of the plane. In this case, it does not matter what plane is used, as a sphere is symmetrical in all axis. Next, add dimensions. A key tip for this is to make the block larger than the sphere. If the block is smaller than the sphere, you can still adjust its dimensions after the mold is complete. You can use the diameter of the sphere as a reference of the block's size.
Once you have these two parts, create a new assembly file in SolidWorks and add the two parts. You can use the perspectives and drag/drop for the objects to intersect (INSERT INSTRUCTIONS FOR INTERSECTION). Note, if the part is larger than the mold block, don't worry. That can be adjusted later when the intersection is removed.
Select the body (solid/extruded block): Go to Assembly > Edit Component then Insert > Features > Cavity to remove the intersecting part.
Next, set the other object (the object being molded) to invisible to view the mold.
When exiting, remember to rebuild to apply the changes.Assembly in SolidWorks. You will be prompted to insert a part - insert the sphere first and place it (left-click once you select the location) onto the document. Next, go to Insert Component and select the block.
Place the block near the sphere and overlap it if possible. It does not need to be perfect as you can use the different view to drag and drop the block to the desired location. For example, you can view a perspective orthographic to the front plane and move the block along that axis. Repeat for the other views to move the block on those axis and aim to intersect approximately half of the sphere will the block. It is good practice to center the sphere into the block if the block needs to be adjusted later. You may result in the following views:
Next, select the block. Go to Assembly > Edit Component:
Then Insert > Features > Cavity.
A Property Manager will appear and prompt you to select the part that you will be basing the cavity out of. The part you select will also be highlighted in blue (or other colours depending on the SolidWorks version). Note, you may need to move the perspective of the assembly in order to select the sphere.
Click the green checkmark to complete the cavity. You can also exit the Edit Component view.
To view the cavity that you created, right click the sphere part and Hide Component. This will show the block without the sphere.
Make sure that the two parts remain in their original position when the cavity is created. This will allow you to save and rebuild the parts so that the original file for the block will reflect these changes. When saving, remember to Rebuild when prompted.
Now, when you open the block's file, there will be the indentation, or space, deleted through the Cavity with the Cavity function. If the mold's size was not large enough to accommodate the part, you can edit the size of the mold in its respective file by changing the dimensions of the rectangle or the dimensions of the extruded boss/bass.TBA: Screenshots
Congratulations! You have created your first mold!
See the following tutorial for building molds of complex, non-regular shapes.
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Complex Mold (with a more
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sophisticated part)
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For the complex mold, we will be using an aerobody as the example, as this will aid the transition of building molds for the end goal. The process is quite very similar to creating a Simple Mold, however, the challenging part will involve the planning and creation of separation markings, which will determine how the molds are created and have easily identifiable points to how it is connected/mounted to the rest of the car.
(Part updated on March 8, 2019,) the 3D model that is used in this example is: AerobodyAestheticModel_REV2B.SLDPRT, the current version of the MSXIV aerobody. Since this part is created already, you will only need to create the base for the mold, i.e. a rectangular block. It is recommended that the dimensions of the box is not too far fetched from the width and length of the portion of the aerobody that the mold will be made from. While this makes it more convenient for the part to be centered into the block without needing to make major changes to the block's dimension, always aim for a block with larger dimensions than smaller.
To start, create a New Part in SolidWorks. Choose the Front Plane and using use the option to draw a rectangle from the center of the plane. Note, in this case, we use Front Plane because the part we want to mold, the bumper, is in that plane. For the side panels of the car, you would use the Right/Left Planes, and for the top and the bottom of the car, you would use the Top Plane. For other areas, you would need to create your own plane to be optimal for the aerobody. In this example, the dimensions were 2000 mm x 1500 mm with an Extruded Boss/Base of 1000 mm.
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You have created your first mold of the aerobody!
Creating
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Molds through SolidWorks Mold Tools
- Draft + Draft Analysis
- Parting Lines
- Parting Surface
- Shut-off surfaces
- Tooling Split