Currently participating in the #3DInktober2019 challenge on Sketchfab. Here's what I did yesterday for the Day 1 theme: Ring :) Sketchfab: https://skfb.ly/6NJZr
http://www.poopinmymouth.com/tutorial/formal_art_training.html I do some part time teaching and the advice here rings pretty true. Hope it helps. Cheerio
Add an edge loop (or two) at the base of the outer ring instead of outside the perimiter (your third shot). This should give the normals room to transition.
Well, my first Sketch of the Throne: It's composed of Needles as backboard, Rings for arm rest and a Thimble for seating. I'm trying to change the thimble by a Dice