When I measure the distance from the wing to the stab it's equal on both sides so they are sitting square with each other. I also measured from the stab to a center point on the fuselage and it was even on both sides. When it comes to either being square there's no doubt it is right.

From there I can't determine whether the wing is sitting parallel to the horizon or if it is the stab. I seem to be able to measure 5 different ways and somehow find 5 different measurements. Sometimes the stab is right on, sometimes the wing is right on, sometimes I have the fuselage just resting on the work bench, other times I put it in an airplane stand. I just cannot seem to come to any decisive result. I even checked some of my other airplanes to make sure I wasn't crazy.

So what do I need to do to make sure when it's in the air both the stab and wing are parallel to each other and the horizon?