Don't you enjoy the facial expression of the clerk in the plumbing department as you try to explain you are working on a microphone. I think this will do just fine. I may leave the plumbing in its original color and markings just for a conversation starter.

As you can see in the back ground, I finally got brave enough to cut on that rectangle. A little touch up with a file is still needed. Here is a closer picture.

Getting ready to drill the hole for the volume control. Rather than use the pot for the volume control, I was thinking about using the tuning pot for the volume since the shaft matches the size knobs I have. I suppose the only difference is audio taper vs linear taper??