The Hackaday community has been treated to a properly considered piece of Y2K-aesthetic hardware: an ESP32 retro music sequencer built by [3DSage] that wears its clear, translucent case like a badge of honour from circa 2000, right down to a battery that mimics the look of a AAA cell through the see-through shell.
The heart of the build is an Espressif ESP32-S3 module with a built-in display. Input is handled primarily by a rotary encoder, though a second dedicated button and a stylophone-style array of brass rods along one edge of the custom PCB round out the controls, giving the player a tactile way to enter notes directly. That PCB was cut using [3DSage]’s own fibre laser, which puts the build firmly in the high-effort, hand-crafted category.
A Battery Worth Showing Off
The power solution deserves its own mention. Rather than hiding a modern lithium cell out of sight, [3DSage] chose a 666 mWh, 3.7 V lithium battery shaped to resemble a AAA cell. Because the translucent case lets you see everything inside, the battery becomes part of the aesthetic rather than an awkward compromise. It is, as the builder puts it, the demon’s meow for this particular project: all the convenience of a modern rechargeable cell, none of the visual anachronism.
Audio output comes through a phono jack with built-in switching, so the sequencer automatically routes sound to headphones when they are plugged in, falling back to the internal speaker otherwise. It is the sort of small, considered detail that separates a tidy build from a great one.
The ESP32 Retro Music Sequencer in a PETG Shell
The translucent case is 3D-printed in PETG, using settings that [3DSage] describes as hot, slow, and critically layer-aligned. Every layer must line up precisely with the one above it to achieve that see-through quality: crossed streams, to borrow the builder’s own framing, ruin the effect entirely. Anyone printing in a humid environment will want to dry the filament first, as [3DSage] learned from experience.
The raw PETG print comes out translucent rather than fully transparent, but a coat of clear enamel fills the surface irregularities well enough to read through, producing exactly the hazy, frosted vintage look the project calls for. It is the kind of finishing trick that makes the difference between a prototype and something you would actually want to strap to your wrist, which brings us to the most gloriously unnecessary feature of the whole build.
Yes, the ESP32 retro music sequencer is also a slap bracelet. [3DSage] built the wristband around a length of steel measuring tape, cold-worked to hold the curvature of the wrist when relaxed. That steel core is then encapsulated in clear Gorilla tape, sourced from The Gorilla Glue Company, for comfort. Running a raw steel tape measure against your wrist is, predictably, not a pleasant experience, so the encapsulation is rather important. Slap-on wristbands were ubiquitous among younger audiences at the turn of the millennium, and seeing the form factor revived to carry functional electronics is a delight.
The sequencer’s operation is documented in a video [3DSage] posted alongside the build write-up: the first nine minutes cover the construction process, while the remainder demonstrates the finished instrument in use. If the ESP32 route does not appeal, the builder notes that this style of step-sequencer music maker can also be realised on a Commodore 64, or even with discrete components and rope-core memory, which is perhaps the deepest possible retro rabbit hole anyone could voluntarily descend into.
The complete build log, schematics, and printing notes are available through the project page on Hackaday, where [3DSage] has documented every step of the process for anyone inspired to chase that ESP32 retro music sequencer aesthetic themselves.
