Can I make a homemade rat cage? Not to big as my room is small. But Not to small?

I was looking at the rat cages at the store and I seen that they were way to overpriced and not entirely safe for rats. I was wondering if there was anyway I could make my own cage for under 60 dollars. Keep in mind that I need It not too big as I have a farily small room. And i will also be using Fleece as bedding Please any input would be appreciated. Thank you.