In the mid-90's I worked for a company that tried conductive ink to create two-sided routings on single-sided CEM-1 circuit boards (cheap). They were trying to save money. Guess what? They didn't. It turns out that recalls and scrap are expensive.
I loved the comment that drilling some vias would create circuit wormholes.
This looks kind of cool, but is there a practical aplication for this o is it js a joke?
It's fun! Fun doesnt need a practical application.
They sell to geeks, and this is good PR. Quite straight forward actually.
With some circuits, you need to worry about current leak from one side of the board to the other. This eliminates that possibility.
That wouldn't work - the board still has two sides locally, it just has one side globally. So there could still be current leakage between the two (local) sides.