boyett style, tin foil and a lighter.
pretty sure its 1/8"3/16 is what the frame size is. then make templates out of cardboard. trace that to the steel and weld them in.
werdpretty sure its 1/8"
Its pretty easy to do, just make some templates and trace them onto the metal. Cut them out with a saw or plasma and weld em in place. Remember to weld in weldnuts in places that need bolts because you wont have access behind there anymore. I forgot this in a few places and its a pain. Take your time welding to make sure you dont warp the frame.