I finished a bunch of slippers yesterday. This photo just shows the ones in Thing 1's size. I made other sizes in both shades of blue, but really, you get the idea with these. I had some trouble with the lighter blue - my zigzag stitches kept skipping. Since the others did fine (both before and after the light blue troubles), I think that it's that particular fleece and not my machine. Fortunately, that fleece is now used up! The grey ones in the lower right are made from a sweatshirt fleece I bought on eBay about two years ago. (I got either ten or fifteen yards - don't remember which. This is great stuff!) I should have made those a size bigger, as the sweatshirt fleece doesn't have as much stretch. They fit Thing 1 great when they're on, but they are really hard to get on! We're going out of town for a few days, but I'll cut out the next size when we get back. He loves those, as they match a sweatsuit I made him a few months ago.
I've thought about putting gripper fabric on the soles but haven't gotten any yet. Our house is almost entirely carpeted, so traction isn't too much of an issue here. And since Thing 1 wears these like socks, I'd hate to add any bulk and make it difficult for him to get shoes on over them. But I think that it would work just fine to add gripper fabric, or even paint the soles with fabric paint. I love the ease of sewing this pattern - there are three pattern pieces, and it literally takes me about twenty minutes to sew a pair. The pattern does not recommend using a serger, as the serged seam can feel irritating to the skin, but I serge them anyway for Thing 1. I tried it on his first pair, and he isn't bothered by it at all. For mine, however, I just use a narrow zigzag stitch.