Out of need I decided to make a shower shelf. It is made to be mounted on a 22mm rod (which seems to be a norm for holding the shower heads). It holds very good on the rod, without sliding down, even with heavy load. On the picture you can get a feeling how many bottles fit there. Also, it has an option for addons: 4 of the drainage holes support the head of a hex screw, so you can mount something from the bottom with a nut. I will later add some addons for shavor holders and similar - until then feel free to design your own (and share it).
The build consists of 5 parts to be printed and some smaller supplies from a hardware store. First and most importantly, you need the base plate plus the counterpart for the mount. Followed by the two leafs (small and large) and a rim that holds the shampoo and his colleauges in place.
Additionally to the printed parts, you need:
For assembly, first put the M3 nuts into their holes. Then you need to first mount the base plate to the rod with the small counterpart for the mount and after put the leafs, then the 4mm rods plus the rim.
Have fun printing it! And play with the color combinations - I would be happy to see how your make worked out :-)
If there is a request for another diameter, leave a comment I will see what I can do.
Credits: The design idea I got from another model (https://www.printables.com/model/215518-leaf-soap-dish).
The author marked this model as their own original creation.