Ever since we completed the bathroom renovation last June we have planning to put in a dual shower head. When creating the shower area we went with a walk in pan and large stall which we designed to easily fit 2 people. We had to get the reno done quickly for the refinance so adding in the dual shower head was the last item on the list. Only a little over 6 months later and we finally crossed it off.
For the extension piping on the wall- 1/2 inch copper piping with appropriate fittings & black paint all available at your local hardware store
A second shower head (rain shower head) with an extension shower head arm if needed
A 3 way shower diverter which threads on behind the existing shower head
First we sweated together all of our piping (1/2 inch copper) with a propane torch using proper copper plumbing techniques. Next we painted the piping black and fitted it to the wall with plumbing brackets (also painted black). Then we attached the 3 way splitter behind the main original shower head and attached the hose to the plumbing pipe on the wall (other end attached to splitter). Lastly we connected the piping on the wall to the second shower head. The splitter allows to have one head, the other, or both heads on at both times-my favorite luxury!