Update: I decided to open up the bobbin holder for commercial use (01.11.2017), please give proper credit to me (linking back here, and using the printout tag) when using the design.
Enjoy the design!
Check out the "Sew Easy!" Group here at Thingiverse. It is all about sewing supplies, 3D printed fashion and tools related to threads and fabric http://www.thingiverse.com/groups/sew-easy"
You can have a flat bottom for easier printing or a rounded one.
Please post a picture of your print, I love seeing the different prints of my designs.
Cura Standard Settings :
0.8 mm Nozzle, Fast, No Support