And a spring together with an electro-magnet can be made into a relay. They're big and slow of course, but they do the same thing as a transistor. If you can ma

And a spring together with an electro-magnet can be made into a relay. They're big and slow of course, but they do the same thing as a transistor. If you can make metal into a wire you can make them. In the 1940s computers were electro-mechanical.