Here is the finished variable capacitor. Installed on a crystal shortwave receiver.
Step 16: The insulator
Look for something that will insulate the rotor's axel from the end plate/chassis. Like for example a rubber hose from a fuel line of an automobile. Since i don't own a car. I just used a plastic pen for a bushing. Note: look for the right pen before you make the top hole bigger. Don not drill until you have your bushing:-)