Inspired by the user intofocus's design ( https://www.thingiverse.com/intofocus/designs ) for a filament clip, and by a stubborn roll of filament that didn't have quite enough leftover filament to reach the locking hole in the spool :-) ...I elected to take a stab at designing my own, while also demonstrating how to use Fusion360's parameters to help quickly iterate digital models. The clips are simple enough to use by either sliding them onto the filament itself, or by pressing the filament into the open clip area. It's a snug fit so it won't let the filament unwind itself from the spool.