That's an interesting read DC, haven't read it all yet but did read the bit about him using an epoxy to basically glue the steel sections together.
Have you done much research on this way of manufacturing a frame? The guy doesn't seem to go into to much detail & I couldn't see much on the link he provided but haven't read that properly either.
He mentioned using west systems 207 which is just a hardener so not sure what resin he used plus there is no mention of ratios for resin, hardener or fillers although there would have to be a low volume of fillers in it if you can pour it.

Determined to get some epoxy in your build somewhere aren't you lol.