On thursday night Burren and I did some milling of the plates and practised bending the 1/4" stainless steel tube.
In the past I have avoided swagelok because their fittings are twice the price. Instead I would run around to lots of different stores and when I couldn't get things locally wait weeks for parts to come from overseas. I had heard good things about swagelok compression fittings (from a ex sales rep so i suppose that doesn't count) and they seemed moderately priced so I decided to give them a try. I have to say I was impressed. As it turn out, for the premium you get higher quality parts and good service (who would have thought...). They even got delivered the same day. Amazing!
I still haven't decided exactly how I am going to fly the vehicle. A RC remote would probably be more reliable than joystick through computer so that is what I am leaning towards at the moment. This is how most UAV's work so there is lots of code around. Another issue I haven't resolved is a robust failsafe so in the event of power failure we are not stuck with a pressurised vehicle that we can't de-presurise. All I can think of is a normally open solenoid but there must be a better (lighter) way than that.