What style?
Big Hammers, Fish Trap, MC, Robo, Pearl, BassTrix, etc all have different sizes/weights...The less material equals more baits per gallon
I used to pour 4" fish traps and got around 200 per gallon If I remember right - You will end up with some waste
You can use the remelts and regrinds for backs and the clear for bellys, the salty bass don't care bout a pretty swimbait
If your trying to sell them, thats a different story - The trick is having enough cavities to fill with no down time or reheating