I put down my liner, and then on top of that, large fleece scraps and then on top of that, bunches of small fleece scraps
I've done the elastics in the corners, the rats chew them off almost immediately, total waste of time.
I've used pillowcase style, be prepared for them to try to get in or under it LOL
The corners always get chewed up first, it seems.
What I recently learned is that rats are naturally burrowing animals and a lot of ppl are doing deep pans of soft beddings/litter for them to dig in. Some are even doing something called Bioactive set ups (google it, it's neat!)
I know mine love digging boxes so I'm going to try to find a reasonably priced litter or bedding to use on the bottom of their cage.
BTW cool patchwork job, very colorful!