I recently ran into an issue with 3D mesh alignment through scaling where I needed the edges to match up at any scale. Here is the mesh:
It's a basic trapezoid, but with a ramp at the top. The goal is to have these side-by-side going up in a spiral, but here's the problem when they are scaled up in measured units:
The edges of the ramps do not align because the ramp itself was also getting scaled. The fix that I used for this is splitting the mesh into 2 parts: a uniform base, and the ramp itself that will never have its up-axis scaled, and will only sit on top of the base: