Capacitive touch sensors are a great way to add external controls to a waterproof enclosure. There is no need to drill holes or worry about gaskets and O-rings. These sensors will detect your touch right through the plastic case!
Design your panel
You can draw it by hand, or with your favorite drawing tool and print it on some heavy card-stock.
Cut the touch-pads
Cut pads from copper tape. About 1/2" square is a good size for buttons on a touch-pad.
Attach the touch-pads
Peel the release paper from the back of the copper tape and stick the touch-pads to be back of the panel so that they align with the buttons on the front.
Attach the Wires
Solder wires to the copper touch-pads. For this example, I used a 6-conductor 0.1" socket cable with one end cut off to simplify connections to the breakout.
Adjust the Wires
Bend the wires away from the panel. The wires will be touch-sensitive too. To prevent accidental false touches, we want to keep them away from the panel surface.
And Test
Connect the cable to the breakout. Power it up and test your control panel. Touching each button should cause a different LED to light up.
Connect to your Circuit
The output signals are 'active low', so they can replace any pushbutton that shorts to ground - such as the buttons on the RGB LCD shield. You can leave off the buttons and solder directly to the circled pads, or (if your shield is already built), just 'tack-solder' the wires to the legs of the buttons.
When you put it all together, you will have a completely sealed, touch sensitive control panel!
