I use a tumbler (6 minutes) to powder coat my cast boolits. Then dump into a colander to separate the powder.
I've hot glued six bullet trays to a piece of particle board. I remove the boolits from the air soft BBs with tweezers and put them in the cavities upside down.
When the trays are full I place a baking sheet with a copper baking mat over them and invert. Then remove the tray/particle board. 300 boolits standing upright and not touching.
My convection oven will handle two baking sheets at a time 600 boolits. Preheat to 400 degrees and bake for 28 minutes.