@P3t4: The board and schematic archives are in a transitional period right now (read the stax mafia circuit boards thread). If you're after the solid-state Carbon, I think this post has links to the schematics of the Carbon amp and the GRHV power supply. As for boards, you can get your own made (links to recent Gerbers should be floating around here somewhere), or buy from someone who has extras. It'll help to review this entire thread, as I think it covers every tricky point of the build. Other things to read, and think about:
The original KGSSHV thread has great info on the basics of building an electrostatic amp. It's old and long, but well worth reading.
A few more basics are covered in the old DIY electrostatic amp thread.
If you decide to build an off-board heatsink design (like all Carbon variants), I hope you have access to at least a drill press. A full metal shop would be better.
Depending on your experience with building high voltage circuits, starting with something non-electrostatic — like a Dynalo with GRLV — might be a good idea.