here, which I found from Homemade by Jill's version. I just wish I had made that bottom piece a few inches longer. It's fine, but he's pantless here so it will probably just barely reach over the strap part when he has pants on. Also, the tutorial says to use quilted fabric or batting in between layers, but I did neither. I think whatever kind of non-stretch cotton fabric you have on hand would work just fine.
I think I'm also going to add a couple more strips of velcro for extra reinforcement. Knowing this kid, he'll probably figure out how to get out of it a day or two into our trip. Then he'll just wander around at Thanksgiving gatherings, mooching from various family members like a less annoying, more adorable schnauzer. Well, it might still be annoying, but his parents are the oblivious type that assume everyone else loves him nearly as much as they do :)