Making a sheet metal pattern from a Truncated Cone

 From:  Ditto
10908.16 
Fwiw, there is a software called Lamina out there that takes a 3dm (version 4) and creates flat sheet cutouts with all bells and whistles : www.laminadesign.com

It was quite expensive at its time, but the author lowered the price to a whooping $1.80 (one dollar, eighty cents) for commercial usage.