Here is how I measure my prop angles. I'm sure it's very close to what Avidflyer is doing too.

First, went to Amazon and bought a 12" Bosch level that also projects a laser dot. While I do the procedure in the hanger, the dot is bright enough to do on the ramp.

Since I have a Warpdrive prop, I take all my measurements at the tip of the prop.

First I level the prop using the bubble level in the Bosch. Then I take a measurement (distance) from the tip of the prop to the ground. I drop a plumb bob from the tip of the prop to the ground and using a black magic marker, make a dot on the ground.

Then I clamp the Bosch level to the tip of the prop. It projects the dot on to the hanger floor. I mark that dot on the floor with the magic marker.

I measure from the plumb bob dot to the laser dot and I have two sides of a right triangle. Using a little trig you solve for the included angle, and you have your prop pitch.

Then I pull the next prop into position, and instead of using a level, I all ready know how high the tip of the prop should be from the floor, and I use that measurement. Clamp the laser level to the tip of the second prop and see where the laser dot is on the floor.

It's not hard to adjust the second and third props to exactly hit the mark on the floor.

If I want to adjust the prop 1/2 a degree, say from 12 to 11.5, I calculate how far the leg of the triangle should be from the plumb bob dot, and measure along the floor to make a new dot. Then adjust each prop to hit that dot.

Sorry for the long explanation of the procedure, but am trying to be specific enough to give a complete procedure.

Hope that is useful to someone.

Regards
Rodney