I built this five-passenger bike by cutting apart and welding together the parts from three tandem bikes, and adding a bit of black gas piping where I needed straight tubing. It actually worked too, and I was able to take it for some wobbly rides in the studio! (Though the rear seat was responsible for shifting gears, since my cables weren’t long enough.)
Inflatable hot water bottles were added to make exploding seats (by Jason Singleton and Jessie Voris, I think.)