Anyone built a bone conduction transducer?

In the past I’ve seen projects online for DIY bone conduction transducers, but can’t find any now. Im talking about the wound copper wire versions. If any of you have a link you can share, please do. This is a very important project.
Also, though I have various schematics worked out, however if any of you have come up with an epic mic circuit for loudness and clarity, I’d appreciate it.