I saw this the other day and thought it could be used to light lego models quickly and easily. Looks great, obviously there is the down side of having to draw on the lego bricks, but if it were on a base plate it wouldn't really matter as it wouldn't be seen. You could draw along the base plate to the points needed, a pretty easy and clean solution?  Also not sure if this removable and would clean off the bricks. I don't know, whats people thoughts?

 

 

 

DISCLAIMER: Didn't watch the video.

There are several brands of "silver particle" circuit writing pens around. I think you could simply cut some paper strips, tape those to the inside of your building and use the circuit writing pen to draw circuits. However, in my experience these pens create circuits with rather high resistance, so you'd have to compensate for that. It might be enough to run an LED without a resistor, but it'd be trial-and-error for me. Still, definitely an idea worth pursuing as these pens can be bought for <$10 here in the US.

I think this is a really fun concept