S1, E6: Was a new invention's ability to save a dying president thwarted by a coil-spring mattress? Did one of the greatest medical innovations of the 20th century come from a simple radio enthusiast? Could a seed-planting device really be the inspiration for one of the military's deadliest weapons? And can you believe the futuristic 3D printer is actually 30 years old? We reveal the true stories behind four inventions that made history, made millions for their creators, and impacted humanity for good and bad.