2015-06-25 / Ok, I think I've found my new favorite clip here: http://www.thingiverse.com/thing:635200 I really liked the "Yet Another Filament Clip" by palawanisland and also the "Filament Clip for Spools!" by Bassna. The filament grabbing part of "Filament Clip for Spools!" is great, but these always get knocked off the spool since they grab on the side and my spools are always rubbing elbows with the other spools. The "Yet Another Filament Clip" method of going under two loops is also great, but I found its filament grabbing part not grabbing quite as much as I liked, so I basically drew a new part that mashes them both together. I printed with 20% infill and it works well. More infill is always stronger, of course.