Monoprice Select Mini Idler Arm Holder

Based off of @seagas' extruder clamp which was a great idea, [found here](http://www.thingiverse.com/thing:1710286), unfortunately his version didn't hold my extruder open enough to insert the filament so it didn't work for me.

I just got my Select Mini in Sept '16 when they came back in stock so I'm thinking maybe Monoproce changed something with the extruder clamp. Anyway, this one, slightly smaller, works great on mine.

The premise is that the idler arm spring is tough and sometimes the