Homebrew PCBs

> Why do you say this. We discussed long that this solution is virtually
> eternal...
> 
It is the CuCl2 (Cupric Acid) solution that is "eternal" not the H2O2+Hcl one.
The CuCl2 bath must be prepared beforehand and looked after periodically, you can diy as follows :
770 ml ordinary warm tap water (40°C) (or 500ml if 3% H2O2)
200 ml Hcl (33%)
30 ml H2O2 (35%) (or 300 ml if 3% H2O2)
40 g pure metal copper (chips or electrical grade wire)
Up to complete dissolution, this can take several hours or days ....
I am not a chemist and have never done it myself, but I understand that if you have to use a several liters etching tank, this is probably the best economical and "green" solution.