For those that hate bending down in your cubicle shower to grab your shampoo, but have nowhere else to store it.
I have made three variations of the shelf to suit your different needs.
Shelf_with_holes.stl
This is the one featured in the image as it's the one I use. I have four suction cups (that I bought here: https://www.amazon.co.uk/gp/product/B0894MZ678/) which are sufficient to hold the weight of the shelf and its contents. While it has been fine for me (5 months without a fall - 12/01/24) it depends on things like the surface you are attaching it to. Both shelves fell after about an hour of first being put up, but have been fine since, so just test.
Caulk_shelf.stl
If you want a solution with less sagging and no gaps, you can use this model and some caulk to stick the shelf to the wall. I'd recommend doing this while the shower is dry and not humid, so minimal moisture is trapped behind it.
Caulk_shelf_shallow.stl
This is a shallow (50mm) version of the other caulk shelf. If you don't need the depth then save plastic and printing time!
I printed mine in stone/marble effect PLA from ZIRO (https://www.amazon.co.uk/dp/B01IIAC2MW). The PLA has been fine for several months and the pattern helps hide any layer lines. I made it the model quick thick (and printed 3 perimeters, 0.8mm line width) to ensure it was strong enough. I used a 0.8mm nozzle for this, on an Ender3v2, so it did take around 7 hours and used just shy of 200g of filament.
The author marked this model as their own original creation.