Amazing idea!
Although I was a little bit sceptic, I tried it, and it actually works quite good. I even was able to get a better result with four magntes arranged in a x-shape. Put the glas on the cross of magnets and do as Dave did it. It also helps to say and repeat the following little prayer until the copper is completely removed:
Almighty God
Please help to
Remove the copper
In order to make a
Lowcost PCB.
For thou hast the power
Of increasing the concentration
Of Iron and chlorine in this
Liquid for ever and ever. Amen.
Dave, I know your opinion about religion, and I also didn't believe it first. But this works really better than your procedure.
Greetings!