How To Keep Track Of Type M Bobbins Loaded With Thread

What to do with all of those pesky bobbins.  I've got multiple spools of thread in multiple colors and I like to keep the bobbin loaded with the same size and color thread with the matching spool.

Played with some wire hangers that slipped through the bobbin and hooked into the hole in the top of the spool, but they were unwieldy.

I then tried a piece of paper towel wrapped around the bobbin which allowed the bobbin to friction fit into the spool when stored, but the paper towel kept tearing.  Then replaced the paper towel with a barrel cleaning patch and it worked but the patch was a pain to keep track of.

Finally came up with a solution that is working for me.  You can take a 3/4" male thread to female slip PVC adaptor and slip it into the top of the spool (a little tight, but one could always sand the threads down a bit) and then drop the bobbin into the slip part of the adaptor and it won't fall into the spool.

The nice thing about this solution is that the adaptor can stay in the spool while threaded into the machine.

Attached are a few pictures.

Hope this proves helpful to someone.