Building a manual boost controler

[Andrew7dg]

Has anyone ever tried this and made it work? I am trying to make one. I bought a 1/4" ball barring and was at a hardware looking at the brass fittings. I found a brass T and on the package it said It had an ID of ¼” but when I put the ball barring in, it had way too much space between the fitting and the ball or that’s what it seemed like to me. Just curious if anyone has gotten this to work. Thanks!