Instructables

Wired Cubes - the wiring

video Wired Cubes - the wiring
If you're done folding and assembling your cubes, it is time to add the wiring:

We are going to hide a battery in one cube and a LED in the next one and use our conductive tape to take electricity from one to the other.  Red is for power, so connect to the plus (+) side of the battery.  Black is for ground and it goes on the minus (-) side.  As for the LED, its long leg goes to the red face and the short one to the black.  The last thing to do is help the two cubes connect by hiding coins and magnets in the little pockets on the surface.

There is more.  Our next step will be to add transistors to the mix. 
very cool idea!