Hi Kris.

The Coghlins matchcase is 2.7 inches deep and each bobbin I have is .425 inches high so at present 6 bobbins will fit with a little space over the last one. If you thinned down the top and bottom of each bobbin a little you might squeeze in 7 bobbins.

The metal bobbins are thinner material and have increased capacity but would be more difficult to reduce in diameter to fit in the matchcase.

Mike