So last night I added the octave key. The switch is a small micro switch that had been salvaged from a mouse. The switch has to be recessed into the main tube, so I cut a slot with a small saw. The key on top is made out of shapelock. The hinge point was made by almost cutting it with a pair of dike cutters. you want to the key to be just at the right point where you push it down without taking your finger off the hole.

In this picture you can see where i used the cutters to make a thin area that acts as a hinge.