Dick Cappels has made a DIY LC meter. As usual he has provided full schematics and code so you can build your own.

“There must be half a dozen similar LC meters on the web. Why didn’t I just download one of them and use it? I suppose part of the answer is that I wanted to do some of it myself. As nice as these other projects are, I wanted to make an LC meter that others could copy and get working without very much trouble. That meant that “exotic” components need to be kept to a minimum, and to me, that means no relays or hard-to-find special switches. It also means that the complete design nees to be spelled out in sufficent detial to allow anybody with basic assembly skills to put it together and make it work.

This instrument requires two precision components: A precision capacitor and a precision inductor. You only need to start with one precision component, either the reference capacitor or the reference inductor, and using this meter, you can select or adjust the other precision component.”