Filament spool holder ends for a 10mm bar

**UPDATE 2017-06-19**
*Not recommended approach for a spool holder*

This approach is really awkward as you have to faff about with different spindle diameters, etc. etc. I've gone away from this and now use https://www.thingiverse.com/thing:629381. This is a much simpler, easier to use and more reliable spool holder. I strongly recommend it to you too. It's a bit more material and needs four 608 bearings, but trust me when I say that you won't regret it.

*Original summary below*