The last 40+ years my mother always crafting things. Working with glass, Fimo, knitting, crocheting, stitching and so on. As she realized that a 3D printer is not just a toy but could make useful tools she showed me her spool storage from the sewing machine. All the threads where unwinding a lot and things are getting messy fast.
This little clamp solves her problem. I mean ... lots of little clamps ;-)

After I've printed 50+ clamps from my mother and her sewing group my sister found out, that companies selling those items with a similar design for 1.50 Euro a piece (10 for 14.99 Euros). So the batch of 50 is worth 74.95 Euros. Ouch! Cost for the PETG was about 90 Cents

I can't upload the Fusion 360 files here, but you can get them from my Thingiverse page:

Print instructions

Resolution: 0.1
Infill: 100%
Supports, Rafts: No

Depending on the material and print bed you're using you might want to add a brim.