I built a dripper, the hole was around .024", made 7.5 ish shot, not perfect but you need to get the heat to each dripper even or you end up with some dripping huge shot and others smaller depending on the temp. Its a fine balance to get it all running perfect and quite a bit of messed up shot that looks like popcorn if its too hot or water is too hot, lead gets contaminants etc. I had a small setup and could only make about 3-5 lbs at a time before it got too hot with about 10 lbs waste to remelt that was huge in like #4 size and some that was too small and was like lead powder. Best bet i could think of is to weld together an aluminum pan setup, with the proper angles, as the pressure from the weight of lead in the melting pan changes flow rates as does angle of drippers, height to coolant tank and even temp of coolant all changes quality. I say aluminum because heat conductivity of it is fast and quite even compared to steel which gets hot in one spot and can be 100C difference 4" from it. Even buying one premade i have read isn't perfect, tons of problems getting it just right to make alot but once you get it close( its never perfectly round) shot can be made on the cheap with a little effort from free lead.