Name: Impulse (IMPL)
Created by CRAY. Randomly moves to any of 4 sides but not diagonal. Any material (except conductors) blocks it from going this side. When it touches a conductor, it sparks the conductor and disappears.
Uses: Making electronic things: better randomisers, spark mazes etc.
Name: CRAY
When it gets sparked, it creates an IMPL in 4 sides. Doesn't creates them at the side that already has any element.
Uses: Creating IMPL.
The whole thing can already be made
will make one and post it.
Hope this gives you an impression of how it can be made
EDIT: https://powdertoy.co.uk/Browse/View.html?ID=660945
here is it open in tpt and you will see, a bit big but yeah....