The first two are the set up for our last hamster, and to be honest I found it worked much better with the shelf on the left and the house on the right - in terms of easy access through the top door. For our current hamster I have things the other way round as wanted a different set up, but found it easier with the shelf on the left! On the first two as well, it was set up for an older, 2 year old hamster, so I had extra shelves and the shelf quite low etc with a shallow ramp. For our current hamster, I didn't use the ladder and have a large cork log tunnel partly under the shelf, which makes a ramp they can climb the sides of to get to the shelf, and also a tunnel. The large rat sputnik gives some "overhead cover" as they sometimes feel a bit exposed from above and like to sit under something. It works best next to a shelf where they can climb in easily.
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