Waterproof coating suitable for direct skin contact with detergents

We are the architects on a custom home that is 100% wheelchair accessible. The owner wants a stainless steel custom seat in the shower that has been dipped or painted with a finish that will be both waterproof and soft enough to provide some padding. Can you suggest anything?

Vinyl-dip coating. Sold to consumers as Plasti-Dip, similar to marine dip coatings used on the ends of rope. Comes in various colors, as well as clear. You might want to look into adding a matting agent to give this stuff a better texture, vinyl sticks to bare flesh (remember cheap car seats on a hot day?). It might also be possible to coat the seat with silicone rubber, but I don't know anybody who does that, and it is a very expensive material.