We've been known to have a bit of a penchant for LEGO ourselves, but the kits we snap together usually come with diagramed instructions and have more to do with fanciful medieval castles than brutal alien slaughter, and they sure as hell aren't life-size, functional engineering marvels.
PlumBrothers' 1:1 scale Lancer is one of the most impressive LEGO builds we've seen in a long, long time, partly due to its aesthetically accurate construction, but mostly because of the boggling amount of engineering that went into this thing. Not only is it a working rubber-band gun, but the weapon's rubber payload is loaded into working clips. Once the safety (!!) is disabled, the user has their choice of single or burst firing modes at their disposal. The chainsaw even moves and everything.
Screw gold, plastic is the new hotness.