1/4" Nut Spinner

I didn't want to waste four of 608zz bearings on a spinner.

As I had some 1/4" hexnuts that didn't have the correct thread to fit a camera tripod, I thought I'd use them as weights, which meant I only need to use one bearing.

So I've modified swholmstead's design to take the smaller hexnuts which don't poke all the way through the holder, and also cleaned up aubenc's knurling2 library to get rid of the calls to polyhedron(triangle) and assign() and some debugging/spacing etc.

Note that