Inexpensive and easy-to-build, it is made of a couple of wires, basic electronic components (easily found at any Radio Shack), a switch and a natural power supply (a potato for example).
The Stepper Box (or just ‘stepper') has a three way switch on top of it, one position marked ‘West', one 'off' and one 'East'. 'West' and 'East' are the names given to the two directions of travel possible through the Long Earth - flicking the switch to either causes the user to be transported one world in that direction.
In The Long Mars, is it revealed that the Steppers also work on Mars. Compared to their Earth analogs, the Mars Steppers have to be powered by Martian cacti instead of a potato.
In the universe of The High Meggas, the device that allows travel between versions of Earth is the belt. Belts were invented by Lider, and perfected by Larry Linsay. They are powered by "batteries". They require more power for larger people, and can transport any animal (not only sapient species) to parallel versions of Earth.
- A Blink of the Screen: Collected Shorter Fiction - The High Meggas