My mice LOVE hammocks, all my past mice have loved hammocks too.
I never buy expensive ones though as they just get pooped in! I just use old clothes
A great one my girls loved was an old racer back vest top, folded over in half and all 4 corners tied to the cage....it had loads of levels this way and lots of openings too, my mice were always in it.
Other things to climb on
- Dressing gown cord threaded through the bars (or attatched to the glass) making 'walk ways' or have them hanging to so mice can climb right up them.
-Bungee cords (you know those stretchy things with hooks on the end) plaited together and attatched in the cage. Again my mice loved these.
- Rope ladders.
- Cargo net, you can make your own there are tutorials online.
- Wine racks are always great for climbing.
- Hang millet sprays from the top of the tank, mice will climb up those.