A short MVP demo of drawlab:
Supports single and dual arcs. Works with any 2 lines at any trajectory. Uses a special kind of curve fitting technology that always adheres to the most circular ellipse that can fit between 2 rays and still achieve smooth connections. There is an infinite amount of possible ellipses that can fit between two rays, but only 1 that is the absolute most circular. The final arc or arcs are created as real elliptical-arc-path-segments and can be further manipulated as such.