I make mine mostly by folding. You can also cut the bar when it is squared and re stack the squares. You have to do it go you can get pressure on the area you want to weld. You can also cut a square bar 1/2 way from one side move over and cut it 1/2 way from the other side. Do that to the whole bar then open up the cuts and flatten. Twist it, square it cut it up and re-stack it. You can test an idea by using colored clay.

There are some guys that are amazing.