This was a project I did this past summer for a floor pipe lamp I built for my wife. My goal was to have a dimmer that looked and operated like a valve. It was designed for standard 3/4in black pipe. Any 3/4in pipe or fittings will thread right into the housing. The Bolt that holds the handle is a standard 1/4-20 bolt. While it is not pictured, I also used a lock washer between the handle and the nut.
Here is the dimmer that goes inside
Here are the plastic screws for putting it all together
Here is a link to the Iron Paint I used
TIPS: This was the 3rd iteration of my original design, and one of the big changes was a limited rotation on the valve / dimmer switch. As you can imagine using a big metal valve handle to turn a small electronic dimmer switch is a recipe for disaster. The limited rotation prevents the switch from being turned to far and breaking. This is important to remember when pressing the handle back onto the dimmer post. Everything needs to be aligned just right or you will have a limited rotation.