Magnetic Quick Change Sample Spool (For Makerbox samples, etc)

I didn't actually remix techyg's sample spool, though I did use its dimensions as inspiration when I made this one in Tinkercad. Nevertheless, techyg had the idea, so I wanted to start by crediting his design.

https://www.youtube.com/watch?v=uqAkQ1S4iFc

This is a quick-change sample spool designed for samples from Makerbox and similar companies. The outer dimensions of the spool are 160mm, the inner dimension is 90mm, and the hole through the center is 55mm. It makes use of four 10mm magnets in each spool half, for a total requirement of eight magnets. I used 10mm x 3mm, though 10mm x 2mm or 10mm x 1.5mm ought to work as well.

I designed a few channels into this spool for clamping one end of the filament, and there are holes spaced around the outer circumference to secure the other hand.

This is an asymmetric design, it's intended that you print one thick ("bottom") and one thin ("top") piece and use them together. I went with the asymmetric design as I didn't like the ga