A cardboard bass? Peter Tambroni sent me a link about this. Believe it or not, this actually appears to be for real. For around $50 you can order a kit from Bogdon Music to assemble a two string bass. The sound is not half bad if this YouTube video is for real:
If anybody has actually seen one of these in person or played one, please let me know! This bass doesn’t sound half bad, and you can still do a lot on two strings. Maybe I’ll get one for outdoor gigs–we’ll see.