Nice designs you have there Rofo! I like the boat pendant!
I use some error add +0.3 to the rules , aka ring bands 1.5 mm -> default , pendant loops and hangs 1.5-1.6 mm . General thickness for shell like design range from minimum 1.1/1.2 mm to 1.5 mm.
So I bumped the rules a bit.
And designed all for Hand Polished Brass/Silver/Bronze and WSF rule as base for that bumps.
*all 39 prototypes printed in WSF due financial constrains
Research for ideas took 80% of my time , 10% design modeling in 3D software , and 10% measuring -> this part gave me some unsupportable headaches and no sleep nights.
And I still have some designs on paper drawn for next time , but I think I must split a little time for checking the prototypes and upload the photos and marketing render , another headache job.
Yet I must get used to the basic idea : When you finish something , don`t look back , do something new! And original (thank good to the art books I learn to draw from ... helps this part a bit).
Some will say "research bla bla bla bla bla" , I say : Take a piece of paper , a pen , draw a pendant , now a ring ... have fun! Now check all over the internet if what you did is really original!" Looking at 1000+ images can be hardcore but inspiring in same time.
I did not have a caliper , I bought one , millimeters in real life look different than on screen , and human eyes are error prone.
One nice art book
http://www.amazon.com/Perspective-Made-Easy-Dover-Instructio n/dp/0486404730