Filament Clips
I've been changing colour on a few different 3D prints recently and some of the rolls started unravelling themselves between prints. I took a quick look at filament clip designs and decided upon these simple ones; because they clip onto the filament itself they'll work for all of my 1.75mm filaments regardless of which spool it's on. Obviously the ones that clip to the spool edge are more secure but this suits my needs for now, the only real problem was trying to turn less than a second of timelapse into a watchable video :) (stl here)