These bins hold Copic Markers ready to use. These things are expensive - don't let them get lost!

The 1x2 bin holds 10 markers, the 2x2 bin holds 25 markers, and the 2x4 bin holds 50 markers.

I included the Fusion 360 files for each model. You could make bins of any size, but you'd have to tweak the pattern to get the best fit of the slots.