Thanks for the informative sharing. It has saved me a lot of time!
Do you know why Sketch produces the twisted shapes when applying “convert to stroke” to generate a vector? This works fine on circles, but produces weird result on sharp corners, i.e. rectangles.
In interface design, a good icon creates a link between users and components being displayed, and a successful icon makes that link unbreakable. The question of how to create a successful icon design is actually how to create unbreakable links.