Show them Red Grooms' work and have them do a large environmental piece (if you can) of a stretch of highway, each doing a mode of transportaion. Or, look at Red Grooms' work and you be inspired to think of something that might work with your kids.
By the way, I have 4 large puppet classes of high school macho boys (ration of 17 boys to 8 girls), and boy oh boy do they like making puppets and performing. I laugh everyday watching them sew and curse at the same time (I do control the cursing, but I think you get my drift). And if I let them use the sewing machine (we do most of our work by hand, without machine) you would have thought I let them drive my car in school!