Okay I updated it and there's a sign at spawn that says "-UPDATE- Smaller RS TNT Cannon behind you" basically behind you over the wall if that ones to complicated you'll see the picture below. After it fires you'll have to close the walls with the same lever that activated it so still 1 button but not fully auto as to compress it.
Quote from BuildingAnALU»
Interesting. Though I feel like from initially viewing it that the wires can be compacted much more. This wouldn't be too convenient for survival or having them lined up next to each other if the wiring takes up that much room.