1/2" OD 4130 tubing is supplied with the kit to make the two cross braces for the tanks. With some of the issues I've heard about with the tanks needing additional support from the 2-per-rev vibrations, I used 5/8" tubing instead. The tubing size matches the size used for the pylon supports.
Using a vice to "swage" the blade ends was my last choice to fab the parts. The only other option I am aware of would be to have them made up by a tubing fabricator.
If you are careful, the vice (with a cheater bar on the handle) will form the ends. Of course, flatting the tube to the extent necessary will stretch the material at the edges beyond it's limits resulting in ruptured metal that should be trimmed away. After using a vertical sanding belt to clean up the edges, I used jig saw to square up the slot in the throat. A few drain holes were added as well.
After forming, the parts were sand blasted and the inside was filled and drained using a corrosion inhibiting primer. The OD was then primed and topcoated with a white polyurethane to match the frame.