I've searched some relative terms to see if this was already posted, but it didn't show anything. (or I just suck at searching 😅 ) One sort of similar post would be the pier/dock that allows you to build on it. I do apologize ahead of time if there an existing post. I tried.
I would love to see a buildable surface to help flatten or level some spaces that are a bit uneven and hard to build on. This would not be a tool, but rather considered a building. You would be able build anything on/around it that you would normally be able to on a nice flat grassy surface such as: crops, orchards, houses, decoration, fencing...etc.)
I'm not sure how to mitigate its sizing, or if it would be similar to how fields are built. It could require clay and straw to build up in sections, like walls. Fencing could be done around the perimeter so you wouldn't even be able to tell there's a giant dirt pad there. Pathways/stairs take care of access.
In the end, it's just something I would like to see.