Pricing "design" time

I’ve been asked to design some silver templates (keychains, charms,
pendants, etc.) for a jewelry designer who is then going to turn
around and add crystals, etc. to the silver “bases” that I make for
her. I’m not too worried about figuring out how to price my work -
but would like some suggestions as to how to go about pricing my
designing time. She’s going to give me pictures and ideas and I’m
going to make up the silver pieces from her pictures. What if, after
creating something from her pictures, she changes her mind or wants
the items altered. How do I price for that time? Or what if she
completely changes her mind and I’ve spent hours in designing?
Assuming my work is good and it was just a change in design. What
kind of up-front arrangement seems to work best in this kind of

Use your hourly rate, estimate your total time for the project to
get a ball park price then get half up front to start, put all in
writing. No pencil to the paper until there is money in hand. No
drawing into their hand until the balance is paid. Get it all in
writing. I figure my design time at the same rate as my bench time.
Any changes is still time spent on the project. An hour is an hour
whether I am pushing metal or a pencil. Obviously I do not do CAD
design yet.

Bill Churlik