Super Accurate Precision Level

Ahoy, Homebuilders,

I had need for a super accurate precision level years some ago. They exist, but are costly.
For my needs, I took a 3/8" x 46" neon tube, plugged one end, filled it -w- mineral spirits and enough ATF to give it a bit of color, adjusted fluid for ~~ a 1" bubble, and sealed the other end.
I took an ordinary (good condition) aluminum builder's level, and fastened the tube to it, propped up the middle ~~ 1/16" to create a parabola.
You could pick the crater on the moon that you wanted to aim at.
Enjoy /s/ Bob