If you have a good design which you want to build... then get some high quality tubes!
These are pretty hard to get, but now you can have them.
Top tubes, down tubes, chainstays etc. all available.
Contact firstname.lastname@example.org for more info.
You can also visit Björn's PinkBike profile at http://swissracetech.pinkbike.com/
If you decide to build a frame, please be as careful as possible, so that the story won't end in accidents!