I have found that "hardware cloth" or some call it screen cloth, of about 1/4" squares works great for powder coating. I just pour the coated boolits onto the cloth that rests inside the oven tray and bake. When baking is done, I remove the tray, let the boolits cool, and just flex the cloth a little and the boolits come right off. I was surprised to find that the places on the boolits that contacted the screen cloth were still powder coated. I find this is a lot easier than standing the boolits up in a mini-ice cube silicone mat, and there is no build up of powder on the cloth to worry about. The cloth just gets powder coated over time.