An additional or replacement bobbin for an Ashford Traveller spinning wheel. Open ended design for better visibility.
Print in two parts and fix together with superglue.
Supports are needed for the grooves - it's only a tiny amount of plastic and easily pulls out in one piece. Even so, my first build (at 0.3mm layers) needed some enthusiastic filing around the groove for it to work properly. If there are bumps, it can cause the brake band to pop off.
I will continue to tweak, to see whether a deeper groove and finer layers produces something that requires less finishing.