

Modubu
semi-staggered 38 key split keyboard under 100x100mm pcb
- Size
- 100 × 92 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 47
- Nets
- 44
- Pads
- 442
- Tracks, vias
- 637, 109
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 14 Nov 2025
- Updated
- 17 Dec 2025
Overview
Modubu is an open-source printed circuit board by yuburoll, from the yuburoll/modubu repository on GitHub, published under the MIT licence. It is a 2-layer board of 100 × 92 mm with 47 parts on 44 nets, routed with 637 tracks and 109 vias.
It is built around the RP2040-ZERO. Its parts include 19 diodes, 19 switches, 2 connectors and 1 IC. It belongs with the keyboards and input boards and the RP2040 boards of this library.
Main components
1README
README.md
modubu
semi-staggered(half row staggered, half column staggered) 38 key split keyboard under 100x100mm PCB
The name "modubu" is tofu square in Korean.
Started idea on my old sketch and KeeNoard, finished and polished the idea thanks to the great DYA Dash.
(Really surprisingly, I made this similar layout when I don't know about DYA Dash.)
credit for 우주신제품(wujusinjepum), the anonymous who named this keyboard.
Preparation
-
2x rp2040 zero (boards formly created by waveshare) (Approx. 4-8$)
-
2x modubu PCB Boards (5 boards are 2$ on JLC w/o shipping cost)
-
1x printed case sets, 6 parts total (Approx. 12$ if you buy printed one on JLC)
-
38x diodes (Approx. 1$)
-
22x M2x6 screws, flathead (Approx. 1$)
-
2x PJ320A 1/8(3.5mm) TRRS connector (Approx. 1$)
-
1x 1/8(3.5mm) TRRS cable (Approx. 2$, may TRS cable can take the place.)
-
38x MX Hotswap Sockets (Approx. 4$) (or, use soldering version)
-
38x MX Keyswitches & Keycaps (Maybe this cost varies too much. 10$ on average)
Approx. 37-41$(w/o shipping cost) needed to build one.
Default Keymap

Holding the key triggers front legend.
There is three layers - Num, Mouse, Fn - which can be noticed by the color legends. ◇ Means Transparent; which uses base keymap.
Build Guides
work in progress. sorry!
You can see the images in the folder, which uploaded for build guides. Especially you may see how to solder the controller board, because this uses surface mounting by castelated pins.
This uses qmk to build the firmware. Copy "modubu" folder which is in "firmware/qmk" directory to "qmk_firmware\keyboards" folder, and build it via qmk msys.
Or, simply flash uf2 in "uf2Examples" folder by changing rp2040 zero in dfu mode, which can be executed by holding boot button while plugging in usb c. Vial versions are also prepared.
Notes
(from my reddit reply)
I made this keyboard for very local and ethnic layouts - Especially Koreans.
Koreans have lots of vowels, so we use left hand for consonants and right hand for vowels. The tragedy starts from here: B position is vowel(ㅠ, yu) in Korean keyboard, so very lots of Korean typers press B in right hand, still they use B in left hand when they typing English words.
Many Korean split ergo keyboard users literally suffers with B position problem; and this is one of most stiff learning curve of them. Some exchanges semicolon to B key, some slides the bottom row or have double B (zxcvbnm,./ => /zxcvbnm,. or zxcvbbnm,.) and some just get used to it.
And after the B, Koreans type many word like CamelCaseVariables (eg. past sentence "있었습니다(it-sut-SOUP-nee-da)" types like "dlTdjTtmqslek") - which make home row mods very cumbersome. We may have seperated shift key for this.
So that's why I made row stagger split design with additional keys: But I was surprised that I'm not the first one with this idea and layout.
Licenses
all codes follow MIT license.
all designs and the hardware board follow CC BY-SA 4.0 license.
If you want to make a commercial product, it would be appreciated if you sponsor some bucks for me.

Parts
47| Qty | Value | Footprint | References |
|---|---|---|---|
| 19 | D | modubu-CustomFoot:Diode_TH_SMD_REVERSIBLE | D1, D2, D3, D4, D5, D6, D10, D11, D12, D13, D14, D15, D16, D17, D18, D19 +3 |
| 19 | SW_Push | modubu-CustomFoot:MX_hotswap_reversible-MIRROR | SW1, SW2, SW3, SW4, SW5, SW6, SW10, SW11, SW12, SW13, SW14, SW15, SW16, SW17, SW18, SW19 +3 |
| 4 | SolderJumper_2_Open | Jumper:SolderJumper-2_P1.3mm_Open_TrianglePad1.0x1.5mm | JP1, JP2, JP3, JP4 |
| 2 | AudioJack4 | modubu-CustomFoot:TRRS-PJ-320A_PIN | J1, J2 |
| 1 | LOGO | modubu-CustomFoot:meshgradationNameHole2 | G*** |
| 1 | LOGO | modubu-CustomFoot:meshgradationNameHole1 | G*** |
| 1 | RP2040-Zero | modubu-CustomFoot:RP2040-Zero-RESIZED | U1 |
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Questions
How big is the Modubu PCB?
It measures 100 × 92 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Modubu use?
47 parts, built around the RP2040-ZERO. 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 Modubu KiCad files?
From the yuburoll/modubu repository on GitHub, at the commit this page was made from: the board is kicad/modubu.kicad_pcb and its schematic kicad/modubu.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Modubu 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).