Plumbcheck gizmo to verify X-Y-Z axes are orthogonal

I had trouble getting the Z axis on my TwoUp to be orthogonal to the XY plane, both Z and XY were skewed. Once I got it all fixed, I printed this construct to verify all the angles were 90 degrees.

The end of the X axis of the gizmo is cut off to mark it, so I would know which axis is which.