Metal spinning header end cap - GIF

[12bolts]

That must have thinned the wall a fair amount because it didnt "use" much length.

[mwmkravchenko]

That must have thinned the wall a fair amount because it didnt "use" much length.

Maybe 1.5mm if the scale is correct in the video. Soft copper is pretty easy to form. I do it once in a while when I need large bends in copper water pipe installations.