The cheap holder that came with the poop bags broke and I needed a new one. However, I had trouble finding one in a store so I looked to 3D print one. The only problem, I didn't like any of the designs I found. They all required supports, looked weak, or were somewhat difficult to print. So I made my own. It prints quick and without supports all while being sturdy.
The inner diameter is 33mm and should fit most common bags.