I’m not sure they do. You’ll need a welder, level 3 fabrication and scads of pipes to craft one. Also a steel chain (They’re everywhere in waste sarcophagi) and some metal chunks or scrap.
A telescopic cantilever on the other hand is easier to make. Needing fabrication 2, pipes, metal and wire (not the copper kind)
Pretty sure the boom is rated to lift MUCH heavier loads, as it precludes installing anything else in its square, unlike the cantilever. I know it’s good enough to lift a lighter 17 tonne vehicle, so it’s AT LEAST as good as 308 strength.