Because Boobs https://www.youtube.com/watch?v=wtqTapjrPhM

I see I've been beaten to the comment I wanted to make. Good on you mate!

Agreed! I totally need to do this!

They used either electron beam lithography or ion-beam etching. You basically use an electron microscope to write instead of look, by allowing the beam of electrons to do the damage that you would normally try to prevent by scanning quickly over the surface.
Alternately, you can do the same thing by steering a beam of high-energy ions (usually Ga+ or charged buckminsterfullerene) with magnetic fields.

Holy lack of security, Batman! .... Also, you should totally have swiped the silver nitrate, that stuff is fun to play with.

Some helium could help with that lightening up.