This is a multi-chamber hamster hideout, but you could size it for any other small furry friend. The walls are adjustable, as you can slide the “walls” in and out of the grooves to make rooms. There is enough room for nine walls, but maximum six is recommended. It does not have a bottom as it's meant to sit inside the cage and be filled with whatever bedding you already use. Our little guy loves loves to climb out the hole in the top and has setup his main sleeping burrow in the back center of it.
The walls slip in easily but that means they also fall out easily when placing the hideout. You can scale up the Z axis 0.5% or so for the walls only to make them slightly thicker if you prefer. We just printed them at 100% then put a dab of glue on the edge and let it dry before inserting to create a little drag. The lid just sits on top.