Hi Jon, also re: sharp when mirrored - if you want your elliptical arc to have that kind of sharpness when mirrored you would want to pick the points of the arc somewhere other than directly along the x or y axis directions.

For example if you draw an arc that's a full quadrant like so:



That kind of shape will be smooth when mirrored.

If you make the arc some smaller section of the ellipse instead of having the start and end at one of the quadrant points like this:



then that's the kind of a shape that will have a sharp corner if you mirror it around the x or y axis directions.

If you want just one side to be smooth and the other sharp, then put the side that you want to be smooth directly on the x or y axis direction and the other one not.

- Michael