I was about to mention the 3 focus-funneling devices, but Snakebite beat me to it. Note that the base for those 3 items is obtained from the boss from the Crypt of Home dungeon.
As for tradeskilling, I have a froob engy tradeskiller, and was only able to provide the most basic tradeskilling to my org mates until I reached TL6. I also have a froob trader that can cast Maestro
nanos on my engy and perform psychology based tradeskilling.
As a rule of thumb: in general you need about 5x tradeskills for the QL item you want to build. You may end up with a setup where you have to swap implants to for tradeskilling versus regular leveling. (I had to rely on MP nano skill buffs and trader wrangles to summon pets to level.) I get asked most regularly for Carbonum armor (requires chemistry), Nano Crystals from Instruction Discs (requires ME, EE, QFT, Comp Lit), and Implants (requires Nano Prog). I think I can build VTE's now, but haven't tried.
On occasion I've helped with parts of AI Tank armor building, making other armors (Crawler, Living Dragonflesh, CAS, Junkmetal, etc...), and a few other things, but froobs will likely never manage to build high end items like Spirit Infused Yuttos Modified NCU, which requres over 1500 ME and a tradeskilling item only obtainable from SL.