2 layers277.2 × 107.5 mm
Corne V4 Pro Micro Edition
klouderone/CorneV4ProMicroEdition
The Corne V4 with Pro Micro Micocontrollers, made specifically for beginners and support for wireless microcontrollers
112 parts208CC-BY-4.0
2 layers131 × 93.8 mm
Expensivo
tompi/expensivo7Wireless, diodeless Cheapino-shaped split keyboard: reversible nice!nano PCB, ZMK config and 3D-printed case
- Size
- 131 × 93.8 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 41
- Nets
- 34
- Pads
- 356
- Tracks, vias
- 707, 17
- Pours
- 5
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 26 Sep 2026
- Updated
- 31 Oct 2026
Overview
Expensivo is an open-source printed circuit board by tompi, from the tompi/expensivo repository on GitHub, published under the CC-BY-4.0 licence. It is a 2-layer board of 131 × 93.8 mm with 41 parts on 34 nets, routed with 707 tracks and 17 vias.
It is built around the PCM12SMTR. Its parts include 22 switches and 1 IC. It belongs with the keyboards and input boards and the nRF52 and nRF5x boards of this library.
Main components
1README
readme.mdExpensivo
A wireless version of the Cheapino: same shape and key layout, but with a nice!nano in each half, ZMK and Bluetooth between the halves. Not quite as cheap anymore, hence the name.
- 36 keys (3x5 + 3 thumb keys per half), MX hotswap sockets
- every key has its own pin on the nice!nano: no diodes, no matrix
- one reversible PCB for both halves: the left half is built on the front, the right half on the back
- LiPo battery, power switch and reset button on each half
- optional EC11 encoder on the right half
- 3D-printed case with an optional magnetic cover over the nice!nano
Parts per keyboard
| Part | Qty | Notes |
|---|---|---|
| PCB | 2 | same board for both halves, see Ordering the PCB |
| nice!nano v2 | 2 | or a compatible nRF52840 Pro Micro clone |
| Sockets + pins for the nice!nano | 2 sets | 12-pin single row; the case assumes the nano sits 4.9 mm above the PCB |
| LiPo battery | 2 | fits under the nano between the sockets, e.g. 301230 (3 x 12 x 30 mm); may stick out ~6 mm past the nano |
| MX switches | 36 | |
| Kailh MX hotswap sockets | 36 | MX, not low profile |
| Slide switch PCM12SMTR | 2 | one per half |
| Tactile switch TL3342 | 2 | reset, one per half |
| Keycaps | 36 | |
| EC11 encoder | 0-1 | optional, right half only |
For the case, per keyboard: 16 M2 heat-set inserts (4 mm long, 3 mm OD), 16 M2x5 countersunk screws, silicone bumpers (10 mm), 8 + 8 6x2 mm magnets (8 in the bottom plates, 8 for the two covers).
Building it
The PCB is reversible, so it matters which side you solder on:
- left half: everything on the front side (the side marked LEFT); hotswap sockets on the back
- right half: everything on the back side (marked RIGHT); hotswap sockets on the front
- the nice!nano goes on the same side as its label, components facing up
- bridge the four solder jumpers next to the nano's top pins on the side the nano is on (marked "BRIDGE ALL 4"), and leave the other four open
- the power switch and reset button have a footprint on each side; fit only the one on top
- battery to the pads below the nano, + and - are marked
The schematic shows how it is wired, including which nano pin ends up on which hole on each side.
Firmware
ZMK, built by GitHub Actions on every push (see the Actions tab for the
.uf2 files). The left half is the central and has ZMK Studio enabled.
- keymap: config/expensivo.keymap
- shield: zmk/boards/shields/expensivo
To flash, double-tap reset and copy the matching .uf2 to the drive that
shows up. Flash settings_reset first if the nanos were used before.
Case
OpenSCAD files in case/, see case/readme.md. The top frames print top face down without supports, so do the covers; the covers hold on with magnets and can be left off.
Ordering the PCB
scripts/gerbers.sh writes build/expensivo-jlcpcb.zip, ready for JLCPCB:
2 layers, 1.6 mm, default settings. 5 boards is two keyboards and a spare.
Choose ENIG if you want the copper logo to stay shiny.
How it's made
Everything is generated by scripts, so edit those rather than the outputs:
| Script | Makes |
|---|---|
scripts/build.sh | the full board build: footprint, PCB, routing, DRC/ERC, schematic, case data |
scripts/build_pcb.py | the PCB, starting from the Cheapino board: parts, nets, outline, logo |
scripts/gen_nano_footprint.py | the reversible nice!nano footprint |
scripts/gen_schematic.py | the schematic, from the PCB's parts and nets |
scripts/gen_zmk.py | the ZMK shield pin lists |
scripts/gen_case.py | PCB geometry for the OpenSCAD case |
scripts/gerbers.sh | Gerbers and drill files for JLCPCB |
The pin map shared by the PCB, schematic and firmware is in
scripts/layout.py. Routing is done by Freerouting (downloaded on first run,
needs Java). The scripts expect KiCad 8 in /Applications/KiCad.
License
This work is licensed under a Creative Commons Attribution license.
Parts
41| Qty | Value | Footprint | References |
|---|---|---|---|
| 18 | MX | expensivo:Kailh_socket_MX_optional_reversible | K1, K2, K3, K4, K5, K6, K7, K10, K11, K12, K13, K14, K15, K16, K17, K18 +2 |
| 8 | MountingHole_2.2mm_M2 | MountingHole:MountingHole_2.2mm_M2 | H1, H2, H3, H4, H5, H7, H8, H9 |
| 4 | back | Jumper:SolderJumper-2_P1.3mm_Open_TrianglePad1.0x1.5mm | JP5, JP6, JP7, JP8 |
| 4 | front | Jumper:SolderJumper-2_P1.3mm_Open_TrianglePad1.0x1.5mm | JP1, JP2, JP3, JP4 |
| 2 | PCM12SMTR | Button_Switch_SMD:SW_SPDT_PCM12 | SW1, SW2 |
| 2 | RESET | Button_Switch_SMD:SW_SPST_TL3342 | SW3, SW4 |
| 1 | Battery | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | BT1 |
| 1 | EC11 (optional) | Rotary_Encoder:RotaryEncoder_Alps_EC11E-Switch_Vertical_H20mm | ENC1 |
| 1 | nice!nano v2 | expensivo:nice_nano_reversible | U1 |
Questions
How big is the Expensivo PCB?
It measures 131 × 93.8 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Expensivo use?
41 parts, built around the PCM12SMTR. 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 Expensivo KiCad files?
From the tompi/expensivo repository on GitHub, at the commit this page was made from: the board is pcb/expensivo.kicad_pcb and its schematic pcb/expensivo.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Expensivo design in my own project?
Its repository publishes it under the CC-BY-4.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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