How can a machine extrude a round pasta shape with a hole in the middle (e.g penne), without the middle metal part blocking the hole falling away

Question

How can a round shape be made, when the middle part of the metal creating the hole needs to be attached to something, which would create a gap in the shape

In: 479

Answer 1

And a follow up question, does it work the same way for extruded aluminum tubes ?

Answer 2

And a follow up question, does it work the same way for extruded aluminum tubes ?