Hi, this is really interesting, thank you. Your tips are especially useful and will help me to approach using the hot tool with confidence.
Im glad its helpful!
When finishing a concave or convex edge, do you find that you have to stretch the fabric slightly, where the curved edge lies on the bias?
It would depend on what that melted edge would be doing. If the edge was a seam line or maybe a concave neck line, then I would either not stretch it at all, or only slightly stretch it so as to not warp it out of shape too much. However if the edge was a hem, then I would definitely stretch as I go to counteract the bias.