We recently decide to crate-train our dogs. Even though both are seniors, its been working really well (for us, anyway - the dogs don't seem to be as thrilled about it!) but the crates themselves - well, they're just ugly. And the plastic liners in the bottom of the crates were uncomfortable for my poor arthritic old dogs.
I finally decided to do what I could about it. I had priced some of the beds and cushions available, and they were either prohibitively expensive or too hard to wash and take care of. So, my pups used their ratty old dog bed and a fleece blanket.

Beautiful, huh? I had been puzzling over what to do about the problem for a while when I came across this while cleaning out a closet :

If you're not quite sure what it is, it's a foam mattress topper. We used it for the old guest bed. This one has actually been around for a while, so I didn't feel too badly about cutting it up.

I used my super- precise measuring method of looking at it and guesstimating, and cut it about an inch smaller on each side than the tray that fits in the bottom of the crate.
I also had a pretty, unmatched old top sheet that I had been keeping around, trying to find a use for. It's just a twin sheet, but it was more than enough fabric for both dog beds. I folded it in half horizontally (right sides together) and cut using the same measurements as before (that would be none) but I left an inch or so extra on either side for seaming, and cut down the whole length of the sheet to the fold. You will have some excess fabric if you do this, like so:

That extra length will be useful later on. After I cut the fabric, I simply pinned it, and stitched up both sides from the hem to the fold. Essentially, I was just making a big, long pillowcase. (These are the longest seams I have ever attempted, and they were harder to keep straight than I thought they would be, even with pins!) I turned it right-side out, lay the foam in the plastic tray, slide the plastic tray and the foam in to the case, folded the edge under the tray and slid it back into place under the crate.
Ta-daaaa!

It was greeted with muted enthusiasm, but I think it looks great.
*Edit - I used an old cotton sheet, but I will be replacing this cover - probably with some cotton duck or upholstery fabric - down the road. The sheet didn't stand up well to the dogs 'nesting' habits. On the bright side, though - my larger, more arthritic old pup now loves her padded crate and lays in there even when she's not told to.