So for illustration i have organic type of soap bars that I use now thanks to the TSA liquid drama.
The slimmer ones in the pic are 3 cm exact and I go through varieties that are thicker as well as but thinner.
I hate soap bar dishes as they are usually horizontal & increase the contact surface area;
- more sticky goo/ soap residue ,
- harder soap release for use,
- more loss of soap &
- less efficient use of shelf space
Note: (Currently a corner shelf raised above / around shoulder; Removed the one near elbow height as due to compact bathroom i tended to hit my elbows on it, ouch!).
I was originally thinking of something like a letter holder / envelope holder types of stuff that's typical on a desk, but not sure if thickness would work and material would survive water & soap in the bathroom. I'm guessing some steel/ chrome stuff might survive.
I was thinking on the lines of books & other stuff that are kept vertically (they don't stick to each other so separators may be more essential for soaps)
Open to other ideas.