The first version of my new 52 bat belt was a very simple design- a single layer of 2mm yellow foam glued to a layer of black 5mm foam. The pieces were all glued to nylon webbing, and then velcro was glued on to fasten it in the back.
Here’s a quick template I made for the belt (link). It’s not quite symmetrical and may need a little resizing but should help if you want to make the belt yourself.