[rx78nt1alex]

You can go to any auto parts store and buy a coil of tubing, 3/8ths is good. I think they sell it in 20-25 foot lengths. Or if you know someone in industrial instrumentation, you can get a hold of 3/8ths stainless steel tubing.

The auto parts tubing is soft and is good for the flaring tool. SS is harder, but with a bit of effort, you can flare it. Or just use swagelok tubing unions and ferrules.