Homebrew PCBs

I have been experimenting with H2O2 + HCl.  I just don't like ferric
chloride much.  It's just nasty stuff.  And I was also very surprised
to find 35% H2O2 at my local 'natural' food store for about that
price.  I usually stay away from their 'nutraceuticals' department
because I wouldn't want to ingest anything that they sell, but for
dissolving  copper I make an exception.  The H2O2 is conspicuously
labeled 'dilute before using', though they avoid indicating what you
might want to use it for...