A friend had asked me to make two cone ornaments to replace some broken ones. It was a really great exercise in cone theory. And, allowing for material thickness. I know if I did this again I would be better prepared for some of the effects created by different type joints. When trying to match an existing object that may have slight hand made adjustments.
It is amazing how the cone and funnels workout from a vertex created by their finished sides, extended to an intersection.
You basically just calculate the circumference of the finished cone, from the diameter, and draw an arc the length of the circumference, from the imaginary vertex of each funnel. Created by the finished sides extended to an intersection. You add an extra tab to solder them together. And you have your cones and funnels.
I have some really great old literature on making all these kinds of strange eccentric and concentric cones. If anyone is interested.
Sincerely,
William McCormick