Portal-inspired gadgets before, but this one takes the cake, as it were. The Aperture Science Handheld Portal Device is made from florist foam, and wonderflex, among other parts, and uses a 9V battery to power blue and orange LEDs around the nozzle. On the back of the gun is a bit of splattered blood -- y'know, since we're not all quick enough to avoid the turrets. Hit up the read link for more pictures. Can somebody please throw in some Wiimote circuitry so we can use this thing to play the actual game?
Read - Notes from the creator
Read - Hi-res Flickr gallery