About bending stainless thin-wall tube. I found this do-it-yourself version had an interesting lesson. If the internal bullet is not well-positioned, the interior of the bend concertinas.That was my best uneducated guess but all I’m getting from shops that roll tubing every day is that it can’t be done with thin wall. I don’t doubt you for a second but it sounds like I’ll have to learn enough about it to be able to do it’s myself if need be.
I have made female molds out of hardwood and used a pneumatic hammer or a riveting hammer with a rounded nylon end.could make female molds of each half of each curve and press a piece of sheetmetal into each mold using a block of rubber then weld the mating halves together.