Need help with hardware

I have a device (of my own design) hooked into my pitot-static
system using barbed tee's, breeze clamps and Tygon tubing.
The problem is it is too hard to remove. (And I have to remove
it often since my device is still under development).

What kind of fitting could I put into the line to make it easy
to disconnect? Obviously the end connected to the airplane
would need some kind of shutoff valve, or at least a way to
easily screw in a plug to make it air tight.

As near as I can measure the tubing is 1/4 inch I.D and 3/8 O.D.
I assume this is not the kind of thing I can find at the hardware
store? I looked on-line at Aircraft spruce and other sources of
hardware, but the problem is that there are thousands of parts
with fuzzy (or no) pictures and no explanation of what and how to
use these parts. I guess one needs to be a mechanic to know these
things?

Thanks in advance for any help

~Paul Mennen