Rat toy ideas for an inquisitive Friend?

I recently bought an albino female rat which I named Friend. I have a cage, and in it I've added thick Care Fresh bedding, a large wheel, ceramic food bowl, wooded house, stick bridge, and a cute ladder. She also has some chewing toys for her teeth. But upon researching a little deeper about rats, I discovered how inquisitive they are and how they need their toys swapped often to keep them entertained. So I need some toy ideas for her. Any would help :)