Cup Holder for a Round Bar (e.g., Hanging Chair)

I designed a holder for my hanging chair in which you can place coffee cups.
Also suitable for wine glasses.
The diameter of the bar to which I attached the holder is 21mm.

I fastened the holder with standard small screws.

The holder remains firmly screwed to the bar. The cup or wine glass holder itself can be removed and rotated as desired.

For longevity, the model should be printed from ABS or PETG.