This tray holds 32 bobbins of embroidery floss. I tested it with both DMC bobbins and some slightly thicker ones I had 3D printed and it works with both.

Ignore the seam in the photos, I ran out of filament while printing and haven't printed a second one yet.

It is available with and without hooks for use with Ikea Skadis pegboard.

Ikea Skadis hook by syfq91 on Thingiverse: https://www.thingiverse.com/thing:4964991