Only just spotted this on Google. I make mine using acoustic guitar techniques - bending sides etc. - because I think the cone needs a lot of air space around it to develop its tone properly. It's not easy, though, especially in the horn area on a Tele-style body, where the bends are very tight.

If you're thinking of doing it by routing out a solid body (with or without tone chambers) then try speaking to Andy Solloway at http://sollophonicguitars.co.uk/ I think if I was doing it Thinline-style I'd probably have the top as a separate piece with the soundwell glued to it and rout the back and sides out of one piece of wood. Mind you, I hate routers so I'm probably not the best person to ask.

If you're putting a piezo pickup on the cone as well as a magnetic neck pickup then it will work best with some kind of preamp to take out the scratchiness of the piezo and to help with balancing the impedance between the two pickups. The Bartolini buffer/blend works very well.

Good luck,
Pete