I do not have a hampster or gerbil. But at my local pet store they let you build them for their hampsters if you ask. It is amazingly fun and You can use anything that hey have out of a box at the molment. I love all the little areas for them. For some reason I like to be like in inclose areas, so I always figure the hampsters like to too, so I always give them some little nooks and crannies to get into
