Hmmm, I get the distinct feeling this Engineer would have some back-up equipment that could be used to replace the guns on his mech/platform/whatever when out of combat that'd improve the whole 'repairing/building' mechs thing, given that some of those parts are probably pretty damn heavy XD ... then again, people in lost planet are apparently able to carry around what looks to be a gun weighing several hundred pounds at least while still running full tilt, sooooo, bits and pieces probably aren't a big deal XD