I make my own buns all the time. To get a uniform size, I make balls and then form them inside an egg ring - the round rings you can get to cook eggs in a perfect circle. I found they were the best size to fit a hamburger. If my egg rings were in better shape, I would try rolling the dough and using them like a biscuit cutter, but mine are old and not real flat. I don't really have a measure for how much dough, just whatever your recipe states, make that many balls and then form the buns. good luck.