Here is the Wall for the 2x2 System X plate wit round corner, for Playmobil or other dollhouses that are based on Playmobil. This can then be used to build a huge area, for example for the large villa (Family Hauser on Youtube).

The yellow and red pins (Playmobil) sometimes go in tightly.

I'm still a beginner in 3D modeling and 3D printing