[Ria P]

I didn't express myself too well. By second level i mean another level to go to like your paper folder. Oscar can go underneath it and on top of it so has two options. My dwarf's bin cage has submerged, large houses with flat, removable roofs on each end of her cage so creating a second level and platforms to place her wheel, sand and ceramic mushroom. Both houses are bottomless and filled with substrate and she sleeps in either of them.
The long bendy ladder placed over a coconut hide and cork log in front of her middle window is something you could add for an additional space to run along. Oscar's set up is similar to my dwarf Edwina's and she seems happy in hers.