// hardware prototype · 2025

QUAD·IO

A pocket-sized handheld with four mechanical keys, light in every corner and a tiny OLED. One minimal physical interface for games, prompts and embedded experiments.

ESP32-C3
4× Cherry MX
OLED
WS2812B
Li-ion

▍ drag to rotate · scroll to take it apart

01 · README.md

What is it?

QUAD·IO is a compact, experimental handheld: an ESP32-C3, four Cherry MX switches, integrated LEDs, battery power and a small OLED. The goal was a minimal physical interface that works as a flexible input/output system for mini-games, reactive cues and embedded-logic experiments.

Playable object tactile mini-games, memory tasks, rhythm prompts and simple logic.
Switch-only UI the whole OLED interface is navigated with the four keys.
Visual feedback diffused underglow plus a light per key, so the enclosure becomes part of the interaction.
Wireless & battery runs on a Li-ion cell, pairs wirelessly.
Custom keycaps drawn to match the proportions of the enclosure.

03 · spec.json

Specs

{
  "controller": "ESP32-C3 SuperMini",
  "input":      "4× Cherry MX switches",
  "display":    "OLED, side window",
  "lighting":   "WS2812B per key + underglow",
  "power":      "3.7 V Li-ion → 5 V boost, TP4056 charging",
  "footprint":  "50 × 100 mm",
  "enclosure":  "modelled in Plasticity",
  "grip":       "TPU anti-slip mat",
  "underside":  "light-diffusing polycarbonate",
  "renders":    "Blender Cycles, OLED emission shader",
  "sprint":     5, // days, mostly concept, CAD and production research
  "disciplines": ["CAD", "hardware", "UI"]
}

04 · devlog

How the concept came together

01
Full enclosure planned in CAD, including internal layout, cable routing and tolerances.
02
Weighed a minimal form against practical constraints.
03
Blender renders to check material, light and mood.
04
Materials chosen by function: grip and diffusion.
05
Custom keycaps matched to the enclosure.
06
Components and the energy system selected.
07
Charging integrated into a compact housing.
08
Sprint result: a solid concept base.
09
Worked through the whole hardware pipeline, plus Blender studies of underglow and the OLED.
10
Drafted the software UI for the OLED.

05 · contact

Open for projects.

Hardware, CAD, embedded and interface work. Say hi.