Yet another spool holder

Designing a spool holder for your 3D printer is probably a right of passage. This is my 3rd, and by far the one I'm happiest with.

**Materials:**
* 4x 608 skateboard bearings
* 8x 3/8" nuts
* 2x 3/8" threaded rod roughly 6.125" (155mm) in length each

**Instructions:**
* Print two of the rollers
* Print two of the sides
* Press fit some 608 skateboard bearings into the circular holes in the sides
* Press fit a 3/8" nut into each end of the rollers
* Thread the threaded rod through the nuts in the rollers until there is an equal length protruding from each end
* Place the roller assemblies between the sides with the rods in the inner bearing holes
* Thread the remaining nuts on to each end of the threaded rods, tighten.

I also included a shim.stl file that I used to build up the inner diameter of the bearings I'm using (I found some Peer 7R6 bearings for cheap at a local surplus store). You won't need them if you're using standard 608 bearings.