I have used ferric chloride for etching copper circuit boards. You
start with a copper plated fibreglass sheet, apply a resist, drop it
in ferric chloride and after a while you have a circuit board just
like the one inside your phone (almost). This should be a similar
process to what you are looking for.
Where to get it - assuming that you are in the US, try Radio Shack
in what remains of their components section. From memory it is not
too expensive. Otherwise a store which sells electronics stuff to
If you want more on using it, there will be plenty of
on the web for circuit board etching.
Regarding adding citric acid. No idea. I would try it straight
before cocktailing. If you want it to act faster, heat it slightly.
Regarding safety. Don't drink it, but I do not think it is too
dangerous. I do not remember my bottle coming with a 90 page list of
warnings. I don't remember it bubbling or making gasses. I think that
the ferric chloride just changes to copper chloride. I think the
instructions on my bottle said to dispose of it by pouring it down
The biggest safety issue I know of with ferric choride is it stains
like something which will mean you will cop endless amounts of flack
from your significant other if you spill it on anything you ever plan
on using again. Get yourself some surgical gloves. It didn't seem to
damage my skin, but took several days for it to wear off.
Hope this helps.