Knob

I had a problem with 3D printed knobs, they are either too tight or too loose.

If you use a small clearance and inaccuracy (especially in corners) makes the knob pretty much impossible to use without filling, a larger clearance and the knob is too loose - there seem to be no happy middle ground.

This design solves this problem by changing the connector - instead of a solid knob with an hole there's a hollow knob with thin "flaps" that are too tight but are flexible so they fit anyway and s