Musical Bookmark: Turning a Theme Song Into a Themed Bookmark!

This project turns a short piece of music into something physical: a wand-shaped bookmark engraved with the waveform of a song. Every time you open the book, you get a small visual reminder of the music that belongs with that story! Essentially turning the sound -> waveform -> real usable object!

For this version, I used Hedwig’s Theme from Harry Potter, but the same idea works for any book, song, or fandom. Dual of the Fates with a lightsaber comes to mind, or Shire theme with a tobacco pipe...

I chose a 15-second clip from the opening of Hedwig’s Theme.

Why only 15 seconds?

1. It’s the most recognizable part of the song
2. Short clips make cleaner, more readable waveforms
3. Using the whole track would just look messy and wouldn't fit on the wand image!

The opening section is also very recognisable so nice to see it visually!

You can get the audio from any youtube video (and get youtube to mp3 download), or buy the song off iTunes!

I loaded the clip into Audacity and did a few simple cleanup steps including

1. Mixed it down to mono (go into Tracks -> Mix -> Mix Stereo Down to Mono), combining the left and right channels into one clear averaged signal. This also makes it easier to 'read' the track
2. Normalised the audio (go to Effect -> Volume and Compression -> Normalize) so the quiet and loud parts (the amplitude) are balanced, rescaling the file so it is even.

This doesn’t change how the music sounds, but it makes the waveform easier to work with later and more visually impressive. Images attached for pre mono and normalise vs post.

Then export this as a WAV file.

Audio nerd note:

I also took an image of the frequency analysis of the clip, which shows what kind of sound it is (instead of just how loud it is which is the waveform). Most of the energy sits in the mid to high frequencies (around a few hundred to a few thousand Hz), which matches the bright, bell melody of Hedwig’s Theme. There’s much less energy in the very low frequencies! I almost put this on the final product, but the waveform is a much nicer visual representation I think!

Next step is turning the sound into something I could engrave. I've attached the Python script I settled on to convert the WAV file into a SVG parametric waveform. You just need to change the WAV_PATH to your own track's path.

The script samples the audio over time and turns the volume changes into a single continuous line. That line is the waveform you see soon engraved on the bookmark.

If you don't have python installed on your computer, get this file and stick it into chatgpt (alongside you wav file) and it should run the python script and output the svg file at the end (attached)!

For my theme (Harry Potter), I picked a wizard wand shaped bookmark as it fits the Potter theme (duh!) and the long thin shape works perfectly for a waveform to run down it!

I kept the design simple so it stays functional as a bookmark and doesn’t damage pages.

On your favourite laser cutting program (forgot to take pictures on my one!) , then insert the wand outline and the waveform svg, align it down the picture and change the settings so the wand shape it cut from the ply and the waveform svg is engraved onto the surface.

I originally thought about 3D printing this, but the laser engraving looks much cleaner in my opinion!

Ta Da! I played around with the shape of the wand and waveform (slightly different endings to the screenshot above), but it comes out really nice!