Spool support, Anet A8

This was inspired by http://www.thingiverse.com/thing:1624641 but that took quite a lot of plastic, so i set out to design an ultra light spool support. So here is the result, about 6-7 grams a piece. I've had a few 608z bearings left over from some older project (those are really cheap) so used them for smoother spool movement.

- Print two pieces for one spool or 3 for two spools (number of spools +1).
- They are symmetrical with respect to the spool, but not symmetrical with respect t