Anyhoo, I made some clips to let me coil up and store my Christmas lights using some old filament spools. Seems like a good way to do something with them since I could not bring myself to pitch 'em, and they don't have any recycling symbols on them (but appear to be ABS). You can find the clips here if you want to organize your lights, and have a bunch of empty spools lying around with nothing better to do.
The design was remixed from Madox's Filament Clip (https://www.thingiverse.com/thing:12516) and Shermluge's Christmas Light holder for rain gutters (https://www.thingiverse.com/thing:3204558).