A guy made an intractables guide (and an accompanying youtube video) that would be an excellent starting point for you: https://www.instructables.com/Recycle-Cardboard-Into-Anything-With-3D-Printing/

It’s a bit involved and messy (and will ruin your blender if you do this a lot), but you can get totally usable parts from this method!

History can teach us a lot.

I did learn this one the hard way. This is excellent advice.

Checks are still used all the time, though, so I’m sure someone has said this recently.