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2 layers146.5 × 75.4 mm3leaf left, the printed circuit board in 3D

After building my first keyboard, a Lily58, I started following r/ErgoMechKeyboards, r/olkb, and r/MechanicalKeyboards.

Size
146.5 × 75.4 mm
Copper layers
2
Thickness
0.8 mm
Parts
62
Nets
99
Pads
253
Tracks, vias
591, 72
Pours
1
Routed
Yes
KiCad
KiCad 9.0 (file 20241229)
Created
27 Mar 2026
Updated
27 Mar 2026

Overview

3leaf left is an open-source printed circuit board by marcuswu, from the marcuswu/leaf-fold repository on GitHub, published under the MIT licence. It is a 2-layer board of 146.5 × 75.4 mm with 62 parts on 99 nets, routed with 591 tracks and 72 vias.

It is built around the BQ24075RGT, XC6220B331MR and 1N4148W. Its parts include 23 diodes, 23 switches, 6 resistors, 5 capacitors and 3 ICs. It belongs with the nRF52 and nRF5x boards of this library.

Main components

3

README

README.md

Leaf Fold

Leaf Fold is a 6x3+4keys column-staggered split portable folding keyboard using Ultra Low Profile (ULP) switches.

[Image blocked: Leaf Fold Pic]

Warning

This board is under active development and is not ready for builds yet. In particular, some of the models, the bill of materials, etc are not up to date.

Introduction and Background

After building my first keyboard, a Lily58, I started following r/ErgoMechKeyboards, r/olkb, and r/MechanicalKeyboards. It was then that I came across the mikefive, a 5mm tall keyboard utilizing Kailh PG1316S keyswitches.

I had always been more interested in low profile keyboards than clacky mechanical keyboards with a lot of key travel, so the mikefive inspired me. I was not ready (and may never be) to reduce down to 5 columns like the mikefive, but I had been intending to learn to design a PCB for some time now.

I felt that the design of the mikefive could easily be altered to be even more portable by either being fully split or by a folding design. After many iterations, I designed and ultimately built the Leaf Fold. This repository is designed to provide the designs for it to allow others to build their own.

The initial version I shared on reddit had a couple of issues I wasn't happy with sharing:

  • The board design prevented bluetooth connections from working
  • The PG1316S switches did not provide a good experience
  • The nice!view screen did not really add anything and was too easy to break when building this keyboard

Since then I have been working on my own switches and this board utilizes those.

Using this repository

This repository contains:

  • Models for the keyboard's case in STEP format with engineering drawings
  • KiCAD project for the PCB

A bill of materials for constructing the keyboard is also available

Build Guide

A build guide is in the works.

TODO

  • Ensure new ULP switches work
  • Build it & test it
  • Create a build guide
  • Update the BoM (build it into this repo so it is versioned)

Parts

62
QtyValueFootprintReferences
22DiodeDiode_SMD:D_SOD-323D1, D2, D3, D10, D11, D12, D13, D14, D15, D16, D17, D18, D19, D20, D21, D22 +6
22Keyswitchkeeblib:My_ULP_ScissorS1, S2, S3, S10, S11, S12, S13, S14, S15, S16, S17, S18, S19, S20, S21, S22 +6
5Ckeeblib:C_0201_0603MetricC1, C2, C3, C4, C5
310kkeeblib:R_0201_0603MetricR1, R2, R3
110mkeeblib:R_0201_0603MetricR4
11N4148WDiode_SMD:D_SOD-323D23
15.1keeblib:R_0201_0603MetricR6
15.1kkeeblib:R_0201_0603MetricR5
15034801600keeblib:CON_5034801600_MOLJ1
1BQ24075RGTPackage_DFN_QFN:VQFN-16-1EP_3x3mm_P0.5mm_EP1.6x1.6mmU3
1HOLYIOT-18010-NRF52840keeblib:XCVR_HOLYIOT-18010-NRF52840U1
1Switchkeeblib:EVQ_P7_PUCSW1
1USB_C_Receptacle_USB2.0_16Pkeeblib:GCT_USB4500-03-1-A_REVAJ2
1XC6220B331MRPackage_TO_SOT_SMD:SOT-23-5U4

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Questions

How big is the 3leaf left PCB?

It measures 146.5 × 75.4 mm and has 2 copper layers, 0.8 mm thick.

What parts does the 3leaf left use?

62 parts, built around the BQ24075RGT, XC6220B331MR and 1N4148W. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the 3leaf left KiCad files?

From the marcuswu/leaf-fold repository on GitHub, at the commit this page was made from: the board is PCB/left/3leaf_left.kicad_pcb and its schematic PCB/left/3leaf_left.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the 3leaf left design in my own project?

Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).