I got the idea for hemp mat to keep substrate in from Luna‘a videos
My set up ideas aren’t so creative. I have a big labyrinth house at one end (doubles up as a shelf). A full width wood shelf at the other end. The wheel screwed to the bars at the back next to the shelf. A couple of hanging rat sputniks next to/over each shelf/house roof, connected by a rat tube tied to the roof. The odd hidey place and bendy bridge at floor level.