Ten44 Keyboard

This project began as a design challenge to build a low-cost, ultra-slim split keyboard entirely from scratch.
There’s no PCB — the keyboard was designed to avoid import tariffs and high PCB production/shipping costs at the time, which would have made the build prohibitively expensive.

The result is a minimalist, portable keyboard that balances functionality, affordability, and design aesthetics.

The keyboard uses the Seeed Xiao nRF52840, chosen for its:

• Compact form factor
• Low power draw
• Integrated charging circuitry
• Built-in Bluetooth capabilities
• Lower cost than the Nice!Nano
• Higher reliability compared to Pro Micro nRF52840 boards (Nice!Nano clones)

The Microcontroller remains partially exposed by design — both for aesthetics and to maintain the super-slim profile while simplifying assembly.

The entire keyboard was modeled in Fusion 360 and includes STEP files for those who want to modify the layout.

You can easily adjust key stagger or spacing by:

1. Moving the key cutouts.
2. Using the Solid → Combine → Cut (keep tools) operation to regenerate the switch and base plate cutouts.

⚠️ Important: Avoid intersecting the cutouts for the microcontroller, the battery cable channels, and be mindful of keycap footprint.

• No supports required
• Minimal material usage
• No screws or inserts — the case snaps together securely
• Designed for standard FDM printers with a 0.4mm nozzle @0.2mm layer height

• Integrated 10440 battery compartment
• Includes a removable access door for easy installation or replacement

Filament notes:

• PLA is more brittle — use care when opening/closing the battery door.
• PETG or ABS offer better flexibility and durability.
• If tight, gently warm the hatch with a hair dryer or lighter (at a safe distance) before operation.
• Frequent use of the door is not recommended.

Only one set of case files is provided — be sure to mirror the parts before printing the opposite half.

The design is based on Gateron Low-Profile KS-33 mechanical switches due to their:

• Low cost
• Wide availability
• MX stem compatibility

Kailh Choc v1 switches were considered but dismissed due to limited and expensive keycap options.

The total keyboard thickness depends on your keycap choice, though the case adds only about 0.4mm — a deliberate detail to conceal the switch bottoms for a cleaner appearance.

Accessible from the bottom of the case using a paperclip or SIM tool.
There are two holes due to mirroring file requirements, but only the one right of the USB port activates reset.

The power switch sits between the BMS and the battery, preventing parasitic drain when powered off.
However, the keyboard must be turned on while charging, since the battery is disconnected when off.

Ideally the exposed connact points should be sealed using either UV resin, small amounts of hot glue, or similar to prevent shorts.

These are 4mm nickel strips with the ends interfacing with the battery folded over on itself multiple times to give the battery a snug fit in the compartment. The battery is oriented with positive terminal facing toward the top of the keyboard and BMS must also be installed in the same manner.

• 44× Gateron Low Profile KS-33 Mechanical Switches
• 44× Diodes — 1N4148 or similar (1 per switch)
• 2× Seeed Xiao nRF52840
• 2× 1s BMS for 10440 battery
  • Optional but highly recommended for safety
  • Ideally with tabs for re-use as battery terminal contact points — otherwise use 4mm wide metal strips
  • Example: BMS on Amazon
• 2× 10440 Lithium-Ion Batteries
• 2× On/Off push power switches
  • Example: Switch on Amazon
• 4× (~4"/100mm) 24–28AWG stranded wires for battery connection
  • To be cut to length
  • Small internal channels are provided for wire routing
• Enamel-coated wire (0.1mm–0.2mm) for matrix row and column wiring
• 22AWG (solid core preferred) for column connections

• Soldering iron
  • Solder
  • Flux
• Tweezers (optional, helpful for wire management)
• Flush cutters
• Multimeter (optional, for continuity testing)
• Hot glue or resin (optional, for securing wires and preventing shorts)

Row Pins:

• GPIO D1 → Row 1
• GPIO D2 → Row 2
• GPIO D9 → Row 3
• GPIO D10 → Row 4

Column Pins:

• GPIO D3 → Col 1
• GPIO D4 → Col 2
• GPIO D5 → Col 3
• GPIO D6 → Col 4
• GPIO D7 → Col 5
• GPIO D8 → Col 6

Notes:

• Wiring is done on the underside of the switch plate.
• Diode orientation:
  • The cathode (striped end) faces the column side.
  • The anode (non-striped end) connects to the switch pin.
• Row wires solder to the opposite switch pin.
• Column wires solder to the diode cathode.

          Right Half:                              Left Half:
R1        [C1]  [C2]  [C3]  [C4]  [C5]  [C6]       [C1]  [C2]  [C3]  [C4]  [C5]  [C6]        R1
R2        [C1]  [C2]  [C3]  [C4]  [C5]  [C6]       [C1]  [C2]  [C3]  [C4]  [C5]  [C6]        R2
R3        [C1]  [C2]  [C3]  [C4]  [C5]  [C6]       [C1]  [C2]  [C3]  [C4]  [C5]  [C6]        R3
R4  [C1]  [C2]  [C3]        [C4]                               [C3]        [C4]  [C5]  [C6]  R4

This project is licensed under the
Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (CC BY-NC-SA 4.0).

You are free to share and adapt this design for personal use, but commercial use or sale of the design, derivatives, or kits is not permitted. More information: https://creativecommons.org/licenses/by-nc-sa/4.0/

Special thanks to the GrabCAD community for the Seeed Studio Xiao nRF52840 Sense 3D model,
which was used as a reference in this project:
https://grabcad.com/library/seeed-studio-xiao-nrf52840-sense-1