Here it is, the Doppelcaster is born (and I must say that I'm quite proud of myself)!
The lower neck is stringed in Nashville tuning (you can buy the set from D'Addario), the upper one is supposed to be replaced by a baritone one as soon as I've saved enough money to buy one. There are two outputs, so I can play each neck with its own effects... Better pictures will come soon, and a demo once I figured out what to do with a double neck guitar... I feel like playing like John McLaughlin but I'm not able to, so I have to find my own way...
You can also noticed that I'm extremely bad at soldering, but after a lot of sweat and some help from Seymour Duncan's wiring diagrams, I managed to do the job - and it works...