Make a hole on the rim with 75 to 80 drill bit. For the valve itself you can use a small spring from an old watch or you can make your own.
- Roll wire around a mini tube or other wire that is the diameter you need, or you can use plastic tube with knife cuts to simulate the spiral pattern on the valve.
- Next, insert a small piece of wire or tubing into your original larger tube.
- Now glue the entire assembly into the hole you drilled in the rim.
The result is a beautiful replica of a stem air-valve which can be further enhanced with weathering.