The pipes are bent using a mandrel, a CNC mandrel, which is good because it means they *shouldn't* have any creases, kinks, or portions of the tube collapsed.
Mandrel bent pipes/tubes is what you're looking for, I guess it's common for them to be sold in kits or assorted pieces. Also FYI Pipe sizing is different from Tube sizing. 2.25" should be tube size, but for example 2" tube = 2" outside diameter, but 2" pipe = 2.375" outside diameter.
I'll be watching that thread to see how you make out when all is said and done. Will need some sound demos when you're done!
