Spool holder support

After printing a pair of [spool holders](http://www.thingiverse.com/thing:1624641) the screw holes did not match up with those on my Geeetech printer so I made some simple horizontal supports to keep it stable.

The holes are 4mm in diameter with room for an 8mm washer.

[Tinkercad model](https://www.tinkercad.com/things/lEN5baQy7XD-spool-holder-support)