Robo3D R2 C2 Multi-Material Feed Wheel

This is just a simple feed wheel for the Robo3D R2/C2 that comes in really handy if you're trying to feed filament with a Mosaic Palette. The fit on the stepper spindle is intentionally very tight, so you'll need to have a pretty accurate feed rate and extrusion multiplier. It's also about the largest size wheel you can get without bumping into the gantry.

In keeping with the Palette theme, I added multi-material arrows to indicate feed direction. Of course, you can leave robo_r2_c2_feed_arro