Anything even remotely mechanical (parts, broken or not.); alcohol, tape, scissors; screws/nuts/bolts; anything that could be used as shrapnel; silk; thread; spraypaint, or anything that's aerosol. Solvents. Lighters. Rope of any sort. Tools. Probably not anything past 2100 in technology, since he doesn't really get anything past very near future and views it as largely unreliable. Jars, especially if they still have the lids. Obviously, knives and weapons, including things that can be repurposed (planks / pipes)
... He's a little weird. XD He wouldn't steal like, 30 pipes, but if there's one just chillaxin' he'd def pick it up XD