I'm new to vacuum forming and am designing an electronics enclosure that will hold a small circuit board, fingerprint sensor and an LCD screen. I've been searching everywhere and I can't find anything on how to design a two piece box, specifically how to design it to assemble together.

I've attached a pdf of the part. I was thinking of putting in gussets in the corners and screwing a flat laser cut piece to the back of it but I can't picture how the mold would be made to make those corner pieces.

I'm using Inventor to design it but the mold making features in Inventor are only built for injection molding.

Thanks for your help!