>I'm trying to think of a way where I would use something strong (it can't bend at all as it could crack the design work on the cake) that uses a handle or something. I wonder if a piece of 5/8" plywood with canvas straps thread through slots at either end, meeting in the middle at a handle, kind of like a carry-on bag, would work.

This whole thread proves my point that programming is The General Practice of Problem Solving. Need ideas for practical problems - ask programmers.