Introduction: TfCD : How to Turn Your Personal Audiowave Into an Earphone Holder

In this instructable you will learn how to turn a personal audiowave of your liking into your own earphone holder so that your cables never tangle in your pockets anymore. To show you how it’s done we picked the catchy guitar riff of “Dire Straits - Sultans of Swing” as an example.

What you need:

  1. Any audio editing software e.g. Audacity
  2. Any screenshot software e.g. Microsoft’s free “Snip” -
  3. CAD software (or temporary licence)
  4. Earphone
  5. A ruler

    If you print the object yourself you might also need:

  6. Plastics glue
  7. A cutting knife
  8. sanding paper
  9. (key files)

Step 1: Taking Measurements - You'll Need Them Later On.

  1. Measure the cable thickness - in our case it's 2 mm.
  2. Measure the widest point of your earphone cable to determine the diameter of the hole in the earphone holder - In our case its 8mm. We chose for a final diameter of 11 mm to provide enough room for frictionless cable movement and taking possible tolerance fluctuations in the final 3D print into account.

Step 2: Defining & Exporting the Audiowave

  1. Choose your favorite track or make your own voice recording to turn into the final shape. We picked the classic “Dire Straits - Sultans of Swing” as an example.
  2. Open the audio software and paste (usually drag&drop) your chosen audio file to see the entire audio wave.
  3. Choose for a part of your desire and cut it so only that part is left. We picked the beginning of the catchy guitar riff, for example.
  4. Important step:
    Zoom in or out the audio wave to find the right balance of shape for your final object. The gaps should be wide enough for your cable to fit in between but close enough to provide a sufficient amount of grooves for the cable to wrap around. You can take rough measurements with your ruler on your screen.

    We aimed for a total object length of 80mm by just wrapping the cable around our finger and measuring the final length. The gaps of the audio wave should be wide enough at the widest point for your cable to fit between them (2mm - see previous step). The peaks shouldn't be higher than 15 mm as they get fragile with increasing height in the final 3-D print.

    Moreover, you might want your final object to fit in your jacket pocket - we aimed for a peak height of 10 mm.

Step 3: Take a Screenshot of the Audiowave

Step 4: Import the Screenshot Into CAD Software

  1. Import the screenshot of the audio wave in a CAD software - in our case Solidworks educational edition.
  2. Create a horizontal construction line where the soundwave is split in half.
  3. In relation to this line create another horizontal line to define the wall thickness of the final print - in our case a solid 3mm.
  4. In relation to the above line (3.) create a horizontal construction axis at the point of origin where the contour-to-come is rotated around. The distance between them - 5,50 mm in this image- is the radius of the hole in the final print.

Step 5: Trace the Contour of the Audiowave

  1. Define the length of the final object. As mentioned earlier it's 80mm in our case, but it could as well be shorter - since you can wrap the cable around the same groove multiple times.
  2. Trace only the upper half of the audio wave with a spline-/path tool. Here you want to make sure to stay as close as possible to the original background while still providing wide enough grooves for the cable. A 2mm reference-line helped us with that. You have to ignore tracing single, high peaks and rather create thick enough hills.

    The right side of the picture displays this best but the shape can be as detailed as you want - just bear in mind that too thin wall-thicknesses can not be printed or would break - depending on the 3D printer you choose. You also don't want your peaks to become too sharp as that might damage the cable later on.

Tip: Lower the opacity of the screenshot for easier tracing.

Step 6: Rotate the Contour to Get the Final CAD File.

  1. From both sides of the contour draw straight lines down to the rotation axis to fully close the sketch.
  2. Use a proper command of the CAD software to rotate this entire contour around the rotation axis to receive the solid body.
  3. Use a hole feature to generate a hole trough the entire body, choosing the rotation axis as the hole's middlepoint and using the diameter that was set in step 1 (11mm in this case).
  4. Now, save the file as an STL file since most 3D printers use this file format.

Congratulations! You can now use an external service such as or to print your file. Good results can be achieved with laser sintering method since this doesn't require support structures that can leave marks on the object's surface.

If you have access to a 3D printer and want to print yourself, follow the next steps to guide your process:

Step 7: Split the File and Print It.

Most 3D-priting DIY projects are realized with printers that use the FFF (Fused Filament Fabrication) technique. Hence, we will elaborate on the next steps using such a printer - in our case an Ultimaker 2+.

The best way for this rather complex shape to be printed on an FFF printer without using any support material is to cut it in half and print the files as shown in the first image:

  1. Use the CAD software again to split the file in half along the rotation axis and save one half as a STL file again.
  2. Import this STL file into your 3D printer's software - in our case, duplicate the file and place them next to each other as shown in the first image.
  3. Save and transfer the new software file to the 3D printer. Use the software's help guidelines to adjust the printer settings.
  4. Start printing.

Step 8: Get Rid of Excess Material

Many 3D printers will require some amount of post-processing for the printed holder. This could include brushing off any remaining powder or bathing the holder to remove water-soluble supports. The new print may be weak during this step since some materials require time to cure, so caution might be necessary to ensure that it doesn't break or fall apart.

In this case:

  1. Carefully use the cutter knife to get rid of the excess material and/or peel it off.
  2. You can use key files and sanding paper to smoothen and polish the grooves and the surface to your liking.

Step 9: Sand the Undersides of the Halves and Glue Them Together

  1. Due to material shrinkage while printing, the bottom sides of the halves might not be fully planar. In order to get an almost invisible parting line in the final object we recommend carefully sanding the bottoms with 180 followed by 320 grain size paper until they're planar.
  2. Next, the halves need to be glued together - use the appropriate glue for the chosen material. In our case we printed with PLA and used a common plastic glue.
  3. Done!

As you can see in the 2nd image the cable+volume control fit just right in the canal.

Step 10: Enjoy Your Customised, Selfmade Headphone Holder!

You can now polish the holder to your liking and maybe even spay-paint it with the correct sort of paint.

Thank you for reading.

Feel free to leave suggestions, concerns and improvements for following readers.