go to lows or home depo and ask for the cardboard rolls they use for carpet, they should have some that they will give you for free, go home and cut it into diffrent sized separate tubes and she will "tunnel" though them, my Herbs love them. she may also enjoy it if you put them on an incline so she can climb, but only do it with the small sections until she gets bigger.
also i made Herby a cardboard box castle, it just sits in a corner pretty much out of the way and its 3 "stories" high a vaccum box(i kept the appliance holder thing inside), then a medium regular cardboard then a slightly smaller box and he has access ways to each level through the roofs and holes on the outside, he spend most of his time in there and seems perfectly content to not have a huge room to play in.
another thing, you have to be careful with this, but i got him a ball to roll outside in, like hamster does. you have to make sure she doesn't get stuck in a dangerous spot but again Herby seems to really like and will get defensive if you try to take his ball away
you could get her a wheel that will be on the inside of her cage that will help her get ride of some energy inside and build endurance, just be sure it doesn't have spokes but is a flat, even surface all around.
my chinchilla is stuck in my room which also isnt to big, but i cut it in half and he comes out to play in his castle and run through his tubes then he jumps in his ball to ask to be set loose in the house by then hes usually tired and takes a nap, drinks a bit, snackes and then runs back down to do it again
, its cheap easy and keeps him from being to bored.
also toilet paper and paper towl rolls, they enjoy playing with them and chewing on them.