Designs on Copper Ovals

Here is a sampling of the Sharpie decorated ovals that I've been working on. I actually have two of each of these (I plan on selling them in pairs).

Today they get dipped in the etching solution (ferric chloride). 

These ovals are a thick gauge (I haven't measured other than by touch) so I plan to leave them in for 45 minutes to an hour.  I really want some definition on each one.

Thanks for stopping by ..
--Natalie