Well, it'd be hard to replicate specific enemy parts in a recognizable way, (unless we already have their parts available), but perhaps you could get close. For instance, let's say you started out in a fairly generic jumpsuit. You defeat a notable CoT boss, and update your costume to include the CoT mantle/cape thingy. Later you take out a Freakshow boss, and upgrade your character with a pair of cybernetic arms. After that, maybe you've taken down a major member of the Devouring Earth and give yourself plant/organic armor legs. Later still, you take down a big name Malta Operative, and don one of their helmets and nightvision goggles, and so on. Admittedly, though, the resulting costume would look a little mismatched, but you'd have "trophies" representing all your greatest accomplishments...