I use a Lee 20lb bottom pour which, I believe is a great pot. I wired up a PID temp. control. The plans are all over the web. Shop, the components real hard and $30-40, should do it, with a bit of scrounging. I can set it to the temp I want, and set the differential to keep it there, within 5 degrees degrees. I set it to 670 and it will stay between 670 and 675. Unattended. I feed "muffins" into this pot from my outside propane cooker. I melt lead,wheel weights, antimony, tin in a cast iron dutch oven that holds about 90-100lbs. This means it is not real big....
no more than 1-1.5 gallons. I make my alloy and pour it into muffin tins to feed my Lee pot. This is good stuff! This makes many many bullets!
Just to clarify, the $30-40 is for the modification only.