1. Make sure both ends are taped shut.
2. Decide how deep you want your box (I want about 1.5 inch to ship canvases), take a box cutter and cut 1.5 down from the top, all the way around. Then do the same with the bottom.
3. Throw away the middle and you have 2 exact pieces that fit one inside the other, for a perfect, strong flat box. I then mark the size on the box and store for when I need it.
