A father built a portable synthesizer for his daughter’s third birthday, and the result looks almost too polished to be a first electronics project. It’s a four-step sequencer with sliders instead of keys, designed so a toddler can make looping melodies just by moving colorful controls. The synth is as much a design and learning story as it is a music gadget, documenting what happens when someone jumps into hardware with no experience and a clear deadline.
The idea started with a Montessori activity board full of switches and LEDs. Watching his daughter twist knobs and flip switches reminded Alastair Roberts of a synth control panel, and he wondered if he could build a musical version. He had no prior hardware experience, which turned the project into an excuse to learn microcontrollers, CAD, PCB design, and 3D printing along the way, all while trying to finish before her birthday.
Designer: Alastair Roberts
The finished synth is a rounded square box in pink or white, with four vertical sliders in bright colors and four matching knobs at the corners. Slide up for higher notes, down for lower, while a tiny OLED screen shows a dancing panda. There are no menus or hidden modes, just a looping sequence that keeps playing while little hands experiment with pitch and tempo, creating simple melodies that shift and evolve with every adjustment.
Roberts started on a breadboard, then realized he needed a proper enclosure that his daughter could actually hold. Off-the-shelf cases were the wrong size and the wrong colors, so he opened Fusion 360 for the first time and slowly modeled a custom shell. A friend’s 3D printer turned those sketches into a real, toy-like enclosure that feels closer to a commercial product than a hack, complete with rounded corners and smooth edges.
The first hand-wired version worked but was fragile, with a nest of wires that broke when he closed the case. That pushed him to design his first printed circuit board, using Fusion’s electronics tools to lay out sliders, knobs, and connectors in a neat, single layer. The PCB not only made assembly faster, but it also gave the interior the same sense of order and intention as the exterior, no hidden messes or shortcuts.
Small design touches make it feel finished. A dedicated battery compartment with a removable cover, mounting posts that let the board screw down securely, and a raised bezel around the OLED so it sits flush with the top surface. The front panel carries his daughter’s name, Alma, turning the synth into something personal. It now lives on a shelf with her other toys and, according to him, gets regular use.
The synth works at two levels. For kids, it’s a fun, tactile way to poke at sound without needing lessons or screens. For adults, it’s a reminder that you can go from zero hardware experience to a polished, gift-worthy object by following curiosity and learning each tool as you need it. Whether or not it ever becomes a product, it’s already a successful piece of design for the one user who mattered most.
The post Dad Built a 4-Step Sequencer Synth Simple Enough for Age 3 first appeared on Yanko Design.