My wife wanted something to keep her bobbin with the same color of thread spool. I saw something similar, but it didn't work for our needs, so I threw this together. The other one I found printed in two parts, and required gluing - I didn't want that, and I didn't want to use supports. The bobbin just snaps into the cradle at the top, and then you put the "tail" into any hole in the spool.

The part that sticks into the spool can either go through the center, or as is often the case, there are holes around the center that also work (typically behind the spool label). The holder is a loose fit (if you turn it upside down, it will fall out), but I didn't think a spring fit would work well, because thread spool holes are often different sizes. My wife is happy with it, which is all that matters :-)

This fits my wife's Pfaff Expressions 715 machine, but it will likely work with many different brands and models. I'd recommend you print one, see if it fits, and then just resize if needed.