i just make sure they have 2 levels (so they can climb) and i use bedding on half the cage for there bathroom and old tshirts and stuff on the other half for sleeping.i use all natural paper bedding. they had an igloo for a while but never got in it or anything.
My guys do not care for hammocks but they really like their hanging pet bed. I make shelf liners and ladder covers out of fleece for the gents. One yard goes pretty far and it's not expensive so you can change the colors/patterns to match the season.
If you make your own liners there is a bonus - you get the scraps. I'm taking all of these and making a burrowing bin now.
Things I've given thought to for other themes: Steampunk - play with colors and patterns accent with toys, Natural - some bird toys are rat safe and my gents love dried grasses so keeping with a color scheme, Funhouse - again, bird toy (mirrors) jingle cat ball (fill with treats) crinkle cut paper in crazy colors and bold mismatched fabrics.
Now this is my kinda thread! Im tottaly into thems too i would like to do something like the adorable nature one i saw on youtube! But right now i have a pink and soft baby blue for my babys with little alphabet blocks and colorful baby toys ! So like a nursery theme i guess?
You could do so many cute things depending how much money you want to spend or how much time you put into it. You could do just about any theme you like - jungle, holiday, food, girly, futuristic,...I think the jungle theme would be pretty easy and cool. There are zebra/ leopard hammocks, jungle huts, and wooden ladders,shelves, perches... Personally I don't spend much on stuff because my guy is destructive. I got this cardboard tube as a scrap from home depot but my rat loves it! It's maybe 1.5 - 2 ft long and doubles as a hide/ chew toy
Once I get my rats and cage I plan on a space theme for them. (Also helps my boyfriend to get more enthused haha) I saw some galaxy prints on tumblr a few days ago that gave me the idea. I'm pretty crafty so I hope to make a space ship for them, either out of fleece or cardboard.
One cage I saw at a friends house really impressed me - it was three small cages attached by tunnels made from old ceramic plumbing, stacked up vertically with about a foot and a half of space between the cages. The tunnels contained old socks that had been firmly attached through drilled holes in the tunnel walls, and the wee ratties would climb up and down the socks like little monkeys. Each cage had a different theme - the top cage was packed out with fabric and more socks that had had hard rings sewn into the openings to turn them into sock tunnels for the inhabitants to sleep in. The second cage down was all divided up into boxes with holes cut into them at varying heights, like a small maze, and this is where food was put - the location changed each time, making the ratties search the maze for their favourite nibble. The bottom cage contained a litter box and a range of small balls, from large metal ball bearings to a tennis ball that had been cut almost all the way through. All in all it would have stood over eight feet high, so not a small structure, but just watching the traffic of rats (I think he had either nine or ten, not sure) moving up and down through the cage environments was absolutely amazing. Basically that just went to prove to me that your own imagination is the only limit - so long as you don't use anything that can be destroyed, like thin plastic tubing or cardboard, you could conceivably make an environment of any size or shape.