Class M Bobbin Holder

M-Class bobbin holder that fits in a standard sewing-table tray that's on most industrial sewing machines.

I used to use a metal tin but it was harder to see which spool was which.

Two versions - a 16-spool holder and a 25-spoll holder with a thumb-grip to slide it or move it out of the way.

2022-05-09 Update: Added a 4-row holder which holds 34 Bobbins. The corners on these are not useable, which is why the Bobbin count is 2-less than the total number of spaces.