I am on work travel for four months and my work put me up in an apartment that is handicap accessible. I have have lots of grab bars but no shelves to put bath / shower items on.
I drew up a shelf that could slide over the grab bar, where the inside is sloped to drain water but the shelf surface is flat to hold soap and bottles.
I would recommend printing BathTrayShelf.stl at 99% of full size to get it to fit into the body better. I printed it at 100% and with the leftover support material on the inside I had to sand the shelf down a bit to get it to fit.
Polymaker PLA High Detail Profile Cura Lulzbot Edition WITH EVERYWHERE SUPPORTS (see attached file)
The rail I designed this for is 38mm in diameter and is 1 3/8" from the wall.
It took about 38 hours to print.