This is a clip to hold a bobbin to a small Mettler thread spool. I'm not sure what other brands of spools would fit.

Just the bobbin needs to be removed- the clip can stay attached to the spool even on the sewing machine.

The ridge to snap the spool into may be too small and can get a bit messy in printing, but it works well enough for me.

Scale it up or down by a few percent to get a snug enough fit.

2 shells, I think.

Probably would work better with ABS