Topzide
TDR MEMBER
The one thing on making your own Nanometer tool, get 7 ft of tubing, measure and mark at 3 ft and 6 ft. Find a board to mount it to, the 3 ft mark is the bottom of the "U". Then line up the 6 ft mark and end of tube for your top line. The extra amount of tubing helps with connecting. This is how the one the I used was made for small engine repair, and it was provided by manufacture as special tool. You can put all you measurement line on the board in 1/4" increments. That way, you wont have to put a tape to it. You can mark 18" mark for where water should be for test. When done with "new" tool, hang on shop wall and wait for the comments. You can tell them it's a "gas" pressure measurement tool. 
