Do you mean a Baja shelf/sun shelf? Our HOA had the community pool overhauled this spring and one of the improvements was to add one. They removed concrete on one side where some of the traditional loungers were and installed the shelf there. It was an expensive project. Granted, the shelf wasn’t the only improvement: they also added a small kids’ spray/bubbler feature where a fountain once was, some plaster work was needed, they had to buy new loungers for the shelf and a new cover for the pool since the shape changed, but the approved budget was nearly six figures. We are in a major Midwest metro area, and apparently no one here likes to do pool renovations. It’s probably like most things...anything is possible if you have plenty of funds.