Review on EZ-NICHES - USA - Preformed Bathroom Recess It Shower Shampoo Shelf (7 x 8 inches) - Tile Ready Niche by Adam Shuler

I have not used it as a 'foot rest' but as one of two alcoves I have built into my shower. The contractor said they were fairly easy to work with "once you understand the layout". He said he always built it himself. I used it as a small alcove under a larger/tall one above. It's like a bar of soap or a soap dish. . . maybe a loofah/sponge. They are very durable and made of very hard plastic. When installed, they must be supported horizontally and vertically with stud bolts. You can then soil them and put tiles and grout on top.