Hi Michael

Thanks a lot for your advice, I will try some of your solutions
I will post a 3dm file if I still struggle with the model,
The model is a jewelry with curved face and I need to fill surface with gems by array command without using arraygem command because it has some sort of a cone curved surface, a bit hard to explain and I might need to post a 3dm file :)

Hello,

Evolute makes D.LOFT, might be worth a try if you are using developable surfaces regularly.

http://www.evolute.at/software-en/evolutetools-for-rhino