I designed this holder for sewing machine bobbins, to keep them organised and untangled.

I printed this on a Prusa Mendel. I set printing speed low and layer height to 0.2mm. I created this in Inventor, so I can't upload a .scad file, but it may have to be adapted for other brands of bobbins. I created this for bobbins with 20.6mm diameter, and it's a nice snap-fit.