Cigar box guitars!
Last year I collaborated with the music teacher @ my school, and we had the kids make cigar box guitars. The 5th grade painted uniqely personal designs on them, keeping some of the wood grain showing, and we used scrap 1x4 's to make the neck, wing nuts and string too! They were fully functional and people got to try them at our art show! I'll try to send a pic if you're interested.