This instructable shows an alternative to etching PCBs with Ferric Chloride.
Ferric chloride is kinda nasty stuff. Quick to exhaust its etching power, non-reusable, kinda pricey, and ends up full of copper salts that are bad for the environment if you’re pouring them down the drain. (For instance: How to Dispose of Ferric Chloride in this FAQ. )
Wouldn’t it be nice if there were an etchant that you could re-use indefinitely so that you don’t have to worry about disposing of the copper, and that could be made in lifetime supply for like $10.00 with ingredients bought at hardware and drugstores? (And it’s prettier too.)
I got seven words for you: Copper Chloride in Aqueous Hydrochloric Acid Solution! (Exclamation point!)