I have loads of short runs of 3mm Faberdashery filament and the Mini Loose Filament Spool (http://www.thingiverse.com/thing:293382) looked like a good way to go with keeping them tidy. But I needed some more slots and slightly larger arms so I made these. The holes fit 3mm filament and I also added some at the top of the arms.
The 70_70_35 version will hold around 20m per slot.
Just remember to wind the filament on the right way so the flat side is against the back of the printer. I wound 2 lots before I realised I had done it wrong, doh!
Edit: arms are now the correct height - 6mm (thanks arachno7)