Look, am sorry I could not carry out this project since at my school, I could not find all the necessary equipment to implement that machine. That I was advised by a teacher that I had chosen to supervise me. However, I still thinking that the key point is the understanding of piezzo-electric materials. These are types of materials which present potential difference when they undergo a deformation. Just try to find out some books. Furthermore, do not think about amplification (since you would fall in the context of the microphone). I wish I could be more helpful, so fill free to contact me directly if you want at firstname.lastname@example.org
Best wishes my friend.
P.S: Would you also refer to the #8 comment of this thread. Loren Booda has talked about something like "Magnetic Damper" and I think it may be interesting. Please check on it.