Filament stand using MM2 roller

We upgraded our printer at work to an MMU2, which came with a set of five spool holders and rollers. However, I modded the MMU2 with a pass-through adapter to allow for easier swapping between our various filaments. By redesigning MTB3R's spool holder to hold just a single roller, we can load 10 spools using only the equipment that came with the MMU2.

Printing notes: after a few unsuccessful attempts at printing these, I found that dropping the speed down to 50% from just before the inner arms meet to just after the outer arms connect resulted in a clean connection, which is what is programmed in the uploaded gcode (mouse ears added for lift prevention.)