How are hollow oatmeal squares made?

Since I’ve learnt that you get every kind of people on the SD message boards, here’s something I’ve always wondered. How do cereal manufacturers make those hollow pillowcase-shaped oatmeal squares? Do they puff up naturally during the baking process like pita breads?

WAG to follow: Unbaked cereal is a bit doughy and sticky, due to the gluten content. I imagine they are molded in halves, and then two halves are pressed together while still in the molds, so the edges stick together, and then the assembled mold halves are heated until the cereal is baked crisp, whereupon they halves open and the dry, hollow cereal square falls out. I can picture this being done at high speed using long chains of mating mold halves, fed by a dispenser that simultaneously measures out the right amount of cereal dough and presses it flat into the mold half to form the convex shape of one side of a square.

I think they’re extruded as a tube and crimped into squares as they come out, trapping a pocket of air in the middle.

I don’t think so. It’d be darn near impossible to extrude these, I should think.

I agree. But I thought (and still think) the OP is talking about the non-latticed type. I wouldn’t describe the thing you depicted as ‘hollow’ - despite the fact that it may have a central void.