To create the mixture without the risk of it splashing around, start with the water, add the HCl and finally the H2O2. The water should be distilled, although tap water might also work (probably just not as well). Do no heat the solution, it works perfectly at room temperature. Heating it will cause the peroxide to break down rapidly. Etching with the HCl solution takes only a few minutes. The solution will turn green from the copper oxide dissolving in it. Agitate the solution a bit to speed up the process even more. There's no need to use a bubble tank. You will want to be able to get the board out of the etchant as soon as the last bit of copper is etched away, to prevent over-etching. You can either use plastic tweezers, or drill a hole in the PCB before etching, and stick a nylon cord through it, which will make fishing out the board piece o' cake. Have a tub with water handy, to wash off the etchant immediately.