I have done some mockup's for some ideas I have for Artrage.
The idea is to have curveguides that work like the real ones.
1. It should be easy to move, rotate and scale it for perfect placement on the paper/canvas.
2. You should be able to mask with it, so if you go over it with the airbrush (or any tool) it doesn't leave any trace where the curve guide is.
3. Maybe the most important feature is that you can lock your pen on the guide, so it always follows the edge of the curveguide/Ellipseguide/Ruler.
That way you can fill out you sketch with perfect lines as you do in the real world.
What do you guys think?