It doesn't take too many nights sat up trying to carefully disentangle a twisted spool of filament to teach the lesson - always clip your filament! Unfortunately, I'm the kind of person who loses things the second I set them down anywhere, so I needed a filament clip that I could easily keep track of.
This is inspired by https://www.thingiverse.com/thing:3268797 - I found that clip design fell off the filament too easily, and was far too easy for me to lose, so I made my own version.
I narrowed the gap at the top of each channel so that the filament snaps in and doesn't easily fall out, and added a ring to the side. This makes the clip bigger, and thus easier to handle for fumble-fingered oafs like myself, and makes it easy to clip it to the edge of a spool, or onto the hanger ring included.
There are two versions of the hanger ring - one designed to contain a 12mm x 3mm magnet, and one with a simple hole for hanging. Take your pick! I now keep one of these rings next to my printers at all times with a dozen or so clips, just to be sure.
Pause the holder ring at 3.25mm to insert a magnet. Will fit a magnet up to 12mm x 3mm.