I had a throttle cable break on a '74 Opel Manta once when I was several miles from the nearest other human being. My kids were still kids then, so I rummaged around the back floorboard until I found a roll of kite string and a Lincoln log. I tied the string to the throttle, ran it through the driver window, and tied the other end to the Lincoln log so I could use it as a handle. I drove the car about ten miles home along winding country roads with the throttle in my left hand, my right hand on the shifter, and steering with my knees and chin. It was actually fun!
I couldn't find a replacement throttle cable anywhere (this was in the pre-internet era) so I went to a bicycle shop and bought a cable I could modify using parts from the original cable.