I liked scottriggle's idea for a "His and Hers" shower toothbrush holder but I don't have a glass door style shower. This design can be used with any standard shower head arm (the threaded metal pipe sticking out of the wall). The outer diameter of the pipe should be 21mm (~13/16") but you may want to measure yours before printing.
To install you need to remove the shower head and slide the pipe though the hole. It's meant to be a very tight fit so the whole thing doesn't rotate with the applied weight of a toothbrush.
I have included both a version with "His/Her" text and a version with no text. I also included just the holding claw to be included in a different design.
Manually swapped colors at the start of layer 21 by using the command M600 with Marlin firmware.