RE: HPI 18SS.
If the MT2 is anything like the MT it's not too hard to put together. I was 14 or so when I put mine together and it came in all those plastic trees and baggies. It wasn't hard but I did mess up a few things when I put together the shock assembly and the towers, so be careful if you are going to put it together, on the old mt the towers aren't very strong so when you screw the shocks on if you go too tight, it will start to split the plastic. Like wood does when you tighten too much also.
That is the only problem I could remember....
I'd give it a 3-4 on hardness but then again if I were to do it today I'd give it a 2 haha. It gets easier as you build.