Cute! I found several links to a tutorial and one said it included pattern pieces, but apparently the site’s been hijacked...link takes me to a page with a bizarre address and a survey that purports to reward you with something too good to be true. Sigh. This sort of thing drives me crazy.
I think you’ve gotten good advice on construction, but those edges are always pesky when batting is involved. I’m making microwave bowl cozies, and it is really hard to not have a bulgy edge if fabric and batting are cut the same size. Cutting the batting smaller works, but I’m not at all confident that it will stay in place in the long run. Hopefully, the stitching on the outside will keep it where it belongs.
If anyone who has the tutorial should contact you with a real address, would you please share it?
Good luck!