Gas Cylinder Valve Indicator

Ever forget to close up your gas cylinders and then donate your bottle gas to the atmosphere?  This project fits onto a 5-lobe Sherwood cylinder gas valve and provides an instant visual indicator if the valve is opened or closed:

The design retains the 5-lobe knob style, making it bigger and easier to deal with when you have welding gloves on etc.

In this example, I printed the “inner valve handle” in green and the “warning color insert” in red.  This will show “green” when the valve has been tightened, and red when it's open.

The “outer valve handle base” has pins to align with the top part, I use superglue to connect those two halves together, taking care not to get any glue on the rotating parts.  I also put a little bit of grease over the moving surfaces to make everything turn smoothly, but that's optional.