Plumbing fixtures already tend to be manufactured to fairly standard sizes, but the Stepbath System proposes keeping each piece to an exact set of dimensions that actually makes them modular. Marc Boada Piqueras' project makes a toilet one unit wide, and a set of sinks two units in breadth.
What you see is a way to integrate bathroom amenities into the wall and floor treatments simultaneously. Each piece would have a flat backing and a base that would contribute to a portion of the tiling on the ground or on the wall. With this setup, a compact restroom could be configured with every module placed adjacent to another; meanwhile, a more spacious room could have the Stepbath System spread out with additional rectangular tiles laid down in between.