A demonstration of a technique for printing two part molds for box-like objects.

This is mainly a demonstration of a technique for making molds of things with flat bottoms (like boxes), and not too useful otherwise (unless you want the exact box I made).

Some helpful notes:

• Model the object you want to create, then subtract it from a solid to get a mold negative. No overhangs or undercuts.
• Leave the top open; that will be your flat bottom.
• Add flanges to the bottoms, both to give yourself somewhere to put some indexing features (I used mortise and tenons with a 0.2mm clearance), and to give you some leverage to pry the molds apart without having to push on the plaster.
• Don't forget to add some draft to your mold, or you will have a hard time getting it unmolded. I used ten degrees on all sides.
• Hollow out the bottom to save on printing time; the bridging won't be on the plaster side so its quality doesn't matter.
• Try to avoid having interior curves on overhanging walls (like I have), or be confident you can print them without dropping threads to the inside.
• Johnson's Paste Wax is a good mold release agent when using PLA and plaster.

The cast in the photos is my first attempt, so don't laugh too much at my poor casting technique.