Can anyone tell me how they put the hole in donuts?

I make donuts very often i first roll the dough using wooden roller then take 3-4 inch of circular cap of bottle and cut then i use half inch size of circular cap of bottle and make small hole in that. You can also use donut cutter to make that shape easily but i use the first method and it works fine.

The dough is then hoisted by hand and loaded into the hopper of a machine called an extruder—a machine that forms the individual doughnuts using a pressure-cutter system. The batch of yeast dough is put into the top of the open machine. A cover is then placed on the machine and the machine is pressurized, forcing the dough into tubes that extrude a pre-determined amount of dough into the desired shape—rings for conventional doughnuts and circles for doughnuts that are to be filled with jam or creme. It takes about 15 minutes for the extruder to push out about 30 dozen doughnuts. An automated doughnut stamper can also be used in conjunction with an extruder. In this case, the dough is extruded in a continuous, unshaped flow through a series of rollers that flatten the dough. Once flattened to 0.5 in (1.27 cm) thickness, the sheet of dough is stamped into doughnut shapes. Read the entire process here http://www.answers.com/topic/doughnut

I used to make donuts and there is a science to it. OK, not really. Right after they make the dough, which is like a cakelike mixture, they put it into a funnel maker. This thing looks like a funnel but with a flour sifter crank. You get the grease good and hot and take the funnel maker and wind it, it pushes out the dough to the grease in the process creating a hole. Before the hole can close the grease has cooked it to the shape it fell in, thus creating a hole.