Im intending to replace the cage door bars in my car, so that they are less invonvenient and the passenger and driver sides match!

I intend to use sleeved and bolted type joins so that i can keep the cage removable, like in drawing Q26 in the blue book, as these are neat.

firstly any tips on welding round stuff and making fish mouths?

they also need to be bent outwards slightly to clear the seats. (the passenger side is currently straight and rubs the seat)
Is there any way they could be belt by hand? lots of heat? sand in the tube? if not anybody got a rough estimate of what an engineering shop will charge?

finally is normal steel ok to use? its just a road car and the cage is there to help when a distracted bmw driver t-bones me, rather that being flipped on a forest stage!.

Cheers Jake