I saw one of those in person once. I was considering one myself, but the guy wanted more money that I had to spend. He told me about Dax though. I have heard that there are two types of these tanks. One with the bulge at the bottom and one without. I posted thoughts on building a tank out of 3"copper drain pipe. here's the reference:
psuggmog (Other Engine)
Forum: Picture Gallery Posted: Wed Jan 10, 2007 7:56 pm Subject: Saabsonettguy's blast from the past.
I have been working on an underbar tank made from 3inch copper DVW pipe. I don't like the readily available flat sweat on endcaps so I working on hammering out rounded ends. It takes repeated anneali ....
This tank could be made with a cheap propane torch since it could be soldered together. I also tried a tank from a british seagull outboard motor. I wrote about that also:
psuggmog (Other Engine)
Forum: Picture Gallery Posted: Wed Jan 10, 2007 11:12 pm Subject: british seagull
The tank looks good, is made out of brass, 2.2liter, has a beautiful fuel shut-off kinda like a AJS,BSA,Matchless,Norton,Vincent,Velocette etc. might of had. The mounting would be easy too. The only real problem is that the fuel filler is almost in the center at one end of the tank. It would have to be moved or the tank installed crooked. They are painted black but here are pictures of black and a stripped one.
Maybe you can find one in your neck of the woods seeing as how you're on the coast.