Homebrew PCBs

DJ Delorie wrote:
> However, I'm guessing my 3 liter tank will need at least a pound of
> copper (16 12"x12" boards) to get to the "sweet spot".
> 

A pure CuCl2/HCl etchant can work with fairly wide range of copper 
concentrations. From memory the copper should be in the 70 to 120g/l 
range for optimum etch speed. So your 3L tank needs 210 grams (1 pound). 
Ok your right. You can dump in 1 pound of copper pipe or old electrical 
cable , and let it bubble for a few days. Just keep the HCl additions so 
it stays acidic during this time. It goes green when finished.