That muffin tin idea is smart. I did something similar with an old ice cube tray from a garage sale. Used it for sorting different screws and nails on my workbench. The little squares kept everything apart, way better than a jar. Problem was it had no lid, so dust got in everything. Ended up finding a plastic container with dividers that snaps shut.
Honestly that's genius. @simonmoore, the dust issue is so real, I've had the same problem. What I did was just drop my whole parts tray into an old shoe box with a lid. It's a free fix and keeps everything totally clean. Way better than spending money on some fancy divided container.