I made a number of leather products as family gifts this x-mas. I wanted to put them in boxes that fit just right. We happened to have a rather large cardboard box waiting to go out for the recycling. I thought, ya know, I can reuse that cardboard and give it at least one more life as a box. So I worked out how you build a design in onshape CAD that makes a box but can then lay the material out flat for the cutting.

flattened box drawing Cutting a box

a cut box

Glued up