You can't use files and stuff because the puzzle says ithat there are no metal objects in the room. (No floppy discs either, probably)
Dude, what part of a DIAMOND file is made of metal? Also, floppy disks (all 5.25", and many 3.5" if the enclosure spring is removed) are made of PLASTIC.
Dude, diamond files aren't made of diamonds. They are ordinary files sprinkled with industrial quality diamond chards the type that can't be used for jewelry.
Alright guy, use a little imagination here, the pertinent part of the file IS diamond, and for the rest of it, there is no material on earth you could construct a file out of besides metal? Carbon composite, high resin plastics, fiberglass? ...There are myriad materials that could serve as the base for my file; why you gotta be a hater?