3D-Printed DIY Contact Microphone

(This page is part of a series See the rest of my contact microphone pages here.)

I developed this contact mic design for my students in 2020. I wanted them to have durable tools with great sound, but build time and cost were important too. I settled on stereo pairs of 27mm piezo discs glued to metal to reduce resonance. A 3D-printed back shell serves as physical protection and cable strain-relief. I have been loaning these to students for several years without much trouble, so I’d say they’re well tested.

I only cover the sensor design here. Go here (LINK COMING SOON) to build an inline stereo JFET preamp that runs on “plug-in-power” from 1/8″ mic inputs.

Parts List

  • 27mm piezo discs with pre-soldered wires. I used Murata 7BB-27-4L0
  • 1-1/8″ dia Aluminum discs, 16GA (About 29mm x 1.25mm). I get these from ebay sellers.
  • 3D-printed back shells
  • Shielded cable (4mm)
  • Optional heat-shrink tubing to differentiate left and right sides
  • Tools: clamps, metal file and/or sand-paper, CA glue (“Super Glue”), thick solvent glue (E6000)

Construction Steps

  1. Print the back shells using the STL file in this download: zlp-3dprinted-contact-mic-housing.zip
    You might need to adjust the OpenSCAD files (and re-render the STL) to fit your actual cable diameter (default 4mm) and aluminum disc diameter (default 29mm).
  2. Prepare the aluminum discs. These are usually die-cut so they have a slightly raised edge. File/sand it flat.
  3. Use CA glue to bond each piezo sensor to an aluminum disc. Make sure it’s centered. Clamp while drying.
  4. Cut, strip, and tin the red/black piezo wires to about 1″ (25mm) length.
  5. Strip the shielded cable. Groom and tin the ends.
  6. Insert stripped cable through the back shell and bend the ends so they fit into the pocket.
  7. Solder piezo wires to the cable in the pocket.
  8. Apply E6000 to the back shell. To support the cable, apply glue to the cable exit (not shown in photo) and pull the cable in/out to work the glue into the hole.
  9. Clamp and let dry. You’re done!