Before I bought some on line, I made one out of the sleeve of an old sweatshirt. I cut the sleeve off, folded it double thickness, cut it down the center and attached velcro. The size of the sleeve was the perfect length to go around Huey with a little overlap for the velcro. I put a peri pad inside that I can change when he tries to mark with it on. I bought some on line after that, but they actually shrunk in the wash & I didn't realize it until we were visiting my parents last week (the main time he is required to wear it), and I picked him up and he grunted like he couldn't breathe. Poor baby, he couldn't! I was squeezing the stuffing out of the poor little creature!
I find they come in quite handy when visiting since my little "mark everything" monster is out of control...