Use this cardboard scoring tool to make folds in cardboard so that you can make your own cardboard boxes or resize existing boxes. It works by making small holes along a line drawn on cardboard. You then can easily fold the cardboard where the scoring line was made. Here is a helpful tutorial on resizing boxes if you need it: https://www.youtube.com/watch?v=qDFf7a9vTFE

Prints as 3 pieces using PLA or other favorite plastic. 20% infill is sufficient:

• wheel - this is a template wheel that you trace onto a piece of sheet metal. You can't really use a PLA this as the cutting wheel because plastic is too soft.
• top and bottom handle halves - these are printed as two mirror halves that are secured together with three M3 bolts. These halves are slightly different because the bottom halve holds M3 locking nuts. Print these with supports touching the bed and after printing remove support under the wheel area.

Requires:

• 40mm x 40mm sheet metal (brass recommended because it is easy to cut)
• three M3 bolts (two 26mm long and one 12mm long)
• three M3 nuts (nylon locking nuts recommended, but regular nuts work fine)

I've included the Fusion 360 model in case you want to modify.