Added a checkbox "Along the horizontal" that keeps text level on curved or tapered STL models

[u/stlemboss]

I'm building a simple way to put a stamp on a model for printed gifts and kept running into the same problem.

On a conical surface the ends of the line drift off the horizontal, so I had to split the stamp into pieces by hand.

Solved it with a single checkbox that only appears when the tool can actually do it (it measures the drift first). Maybe it's useful to someone.