Cutting them out of square tubing is pretty easy. The only tools I used to do it was a grinder, a chop saw and my MIG welder. And you don't need the chop saw, a grinder with a cut off wheel will suffice. The level of precision isn't bad either, I mean, if everything ends up within a 1/4" you're fine.
....
Again, you make it sound easy!
Some of us are coming from different worlds...I do have a grinder but otherwise, I have just basic tools and an only "slightly better than high school shop class" level of mechanical inclination. A MIG welder is not even in my future. Most of the vaguely unusual tools that I have in my garage were bought only out of necessity in doing my engine swap. I'm actually in the process of getting rid of my engine hoist right now.
So the braces that you cut appear to be similar to the designs of the Mopar (etc) bolt-in connectors. Do you agree that they don't help with torsional stiffness?
Are there other kinds of bracing that could supplement bolt-in style bars?