This can be done in Revit, like this:
1) in a generic model adaptive template, create some reference lines, as shown:
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2) Then select groups of lines and do Create Form > Void Form, several times, as needed, as shown below. For each form, select the upper face, and unlock the pad lock. Then select points at corners. Revit will show a temporary vertical dimension from zero. Set that elevation to the required number. As shown here:
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3) Now create a solid box that contains all the previous forms. Select the outer rectangle of reference lines > Create Form > Soild Form, as shown here:
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4) Now use Cut > Cut geometry, several times. Select the positive first, then a negative. Then repeat until all the negative forms have been subtracted. Now you have the mold. Then load this family into a project. Place it on Level 1. Make a section that passes through it. For clarity, I added a surface pattern using VG > Generic models > Cut > Pattern. Now the mold, in section, looks like this:
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5) Now select the family and make it a group. From the section view, select the family and rotate it 180 degrees. Now it looks like this, in section view:
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Now the mold is upside down. If we go to a 3d view, it looks like this:
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And if I cut the family with a section box, for clarity, it shows the internal forms, like this:
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Alfredo Medina _________________________________________________________________ ______
Licensed Architect (Florida) | Freelance Instructor | Profile on Linkedin