Grab, your manufacturing student wasn't the first. Back in the 1940's, a fellow named Macaferri pioneered making plastic archtop guitars, first manufacturing them himself, then under licensing to Selmer (the band instrument people). The most famous player of these instruments was Django Rinehart, the great French gypzy-jazz guitarist. You still find them around in music shops. I don't much care for them myself, but they're out there.

Of course, Ovation has done a lot with synthetics (their inventor was a helicopter designer who knew a lot about the strength, rigidity and flexibility of plastics). And carbon composites are now coming into their own as well. For myself, give me a real, solid-wood guitar any day. But the other stuff is out there.