I don't know about different, but creative you can do. My two like tunnels and boxes of shredded paper. I like the ladder idea because both like to climb stuff. I want to either make or get a cat tree for them to climb. My cats would never use it and I think my rats would climb all over it. I unwound a roll of crepe paper and put it on the bottom of the cage. They went mad for it. Right now, their favorite toy is me. They climb and invade my shirts all of the time. There are some videos on YouTube that have great toy ideas and hammock tutorials. Good Luck!
A drill and pipe cleaners are the two most useful things you can have to help make creative toys Ladders, huts, hammocks, hanging toys, and stuffed boxes/tubes are some of my favourite things to make for them. I use apple wood mostly
My basic building materials are cardboard boxes, a serrated steak knife, and a roll of rippable paper tape (check in a hardware store for this, it's indespensible for building/sculpting with cardboard).
Rats love to explore small dark spaces, and make nests inside. So you can't go wrong taping 2 boxes together with a few entrances, and a hole leading from one box to the other. You can attach them vertically, or make a tower (just make sure it's stable). You can attach oatmeal boxes, stuff the boxes with tissue paper, etc. When they get dirty just throw them away and start over with new boxes. I do this all the time and it keeps my girls on their toes, always having new boxes to explore and play in.
I decided to take a picture of what I made. It takes some time cutting putting holes in them so I suggest doing it while watching tv or something. I've been keeping some cardboard and anything made out of cardboard... such as the duct tape roll (no tape on it).