Finch_Board: Thumb Keyboard

A compact, handheld ortholinear keyboard with tactile switches. Hardware customizable and fully programmable with QMK firmware.

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How many times have you wished for a small, convenient keyboard while setting up your HTPC for your TV or tinkering with your Raspberry Pi? Or perhaps you find touch keyboards not convenient enough for serious typing on your phone or tablet?

This project aims to develop a handheld keyboard designed for thumb typing. With the power of QMK (Quantum Mechanical Keyboard firmware), I believe we can achieve this goal!

Key Features:

  • Optimized for Handheld Use: Designed for easy and comfortable thumb typing.
  • Clean Ortholinear Layout: Ensures efficient and ergonomic typing.
  • Fully Programmable: Customizable with QMK firmware for a personalized experience.
  • Thumb Keys and Shoulder Buttons: Enhanced usability with additional control options.
  • Hot-Swappable: Switches, keycaps, and the controller board can be easily changed without soldering.
  • Pocketable: Compact size makes it easy to carry.
  • Cute Design: Attractive and appealing appearance.
  • Beginner Friendly: Easy to assemble with no complicated soldering required, making it an excellent project for learning about custom keyboards.
  • Wireless (TBD): The Arduino Pro Micro can be easily replaced by a compatible wireless developement board like the nice!nano.
  • Built-in Pointing Device (TBD): Mouse emulation with a joystick. After all, what’s the point of a pocketable keyboard if you don’t have a mouse in your pocket too?


Portable Network Graphics (PNG) - 98.07 kB - 07/16/2022 at 06:59



JPEG Image - 857.19 kB - 07/12/2022 at 12:41


Portable Network Graphics (PNG) - 24.47 kB - 07/10/2022 at 19:32



test layout for keyboard

hex - 49.70 kB - 07/10/2022 at 11:14


  • 1 × Arduino Pro Micro microcontroller board based on atmega32u4 chip for keyboard control
  • 50 × Omron B3F-1050 Tactile Switch with square plunger
  • 50 × A44 or A66 Tactile Switch Cap 8x8x4.4mm color round or square button caps ror 6*6*7.3mm square head
  • 1 × Mill-Max 801-47-010-002000/012000 low-profile pin header
  • 1 × PSP-1000 thumbstick or FJ08K-N PSP style slyding rocker potentiometer

  • Making FinchBoard Legendary: Printing the Custom Legends

    Alex07/14/2024 at 14:24 0 comments

    On a full-size keyboard, I can type using blank keys, but the FinchBoard is a different matter. Sure, I could memorize the layout or write it on the keycaps with a permanent marker, but I wanted something more aesthetically pleasing.

    Since I couldn’t find suitable keycaps with lettering on the market, I came up with the following solution.

    Using a laser printer, I print the letters onto a sheet of glossy magazine paper and use solvent to transfer the toner to the surface of the caps. The keycaps are made of ABS plastic, which becomes soft at 100°C and melts at 300°C. They dissolve well in acetone, and the 647 solvent I use dissolves the caps to about the same extent as acetone.

    Through trial and error, I managed to find the appropriate solvent composition. 

    I mix solvent 647 and isopropanol in a ratio of approximately 1:2 or 1:3

    I found that a mixture with a higher concentration of solvent, such as 1:1, makes the image blurry, while a 1:4 concentration is too weak to transfer the toner. A 1:1 mixture of acetone and isopropanol also works for transferring toner.

    To position the patterned paper and the caps, I printed a cap holder and a lid with 2mm thick rubber glued inside as a press to evenly distribute pressure on the caps. 

    I prepared a layout in CorelDraw, remembering to mirror it before printing.

    First, I cut out the layout along the outline and placed it on the rubber inside the lid. Then, I moistened it with solvent using a syringe and placed the holder with the caps on top. To apply pressure, I initially tried pressing them with my palm on the table, but the result was poor. Using my body weight gave better results:

    Finally, using a vice provided a complete transfer of the toner from the paper to the caps.

    The position of the letters was a little off, so I corrected the layout in CorelDraw.

    As for the durability of the images transferred this way, I’m not entirely sure yet. They don’t rub off with a finger and are resistant to alcohol when gently wiped. However, if you soak the toner with alcohol and rub it forcefully with a napkin, the image can be erased. I think it makes sense to cover the caps with a layer of varnish. An alternative to varnish could be to paint the caps with sublimation paint and then remove the toner, which should leave the plastic under the toner with its original color.

  • I assembled a prototype on a PCB from PCBWay

    Alex01/29/2024 at 11:40 0 comments

    It's been quite a while, but I have some updates to my project.

    First, a big thanks to PCBWay for providing me with high-quality PCBs for this project!

    I managed to put together a prototype keyboard that is significantly better than my first attempt. This time, I used Omron B3F-1052 switches, which are much better than the ones I used previously. Using the right PCB is also much easier than running thin wires on a prototype board.

    I settled on a 5x5 key layout for each hand, which now seems optimal to me. I'm considering adding the missing functions using layers.

    I continue to learn to type on this keyboard, and I can say that it feels pretty good in the hands. I was concerned that the clicking of the switches would be bothersome, but so far, this has not been an issue.

    I also want to work on the keyboard layout. The classic "QWERTY" layout seems extremely suboptimal for typing with two thumbs. I aim to keep finger movements to a minimum and learn to touch-type on a new layout.

    After soldering the switches to the board, I found that they hold up well on their own because their legs spring slightly in the mounting holes. This opens up the possibility for quick switch replacements, which is useful considering that branded switches are surprisingly expensive.

    I also have some ideas on how to 3D print shoulder buttons.

  • First try

    Alex07/12/2022 at 13:32 0 comments

    Finally, I’ve created something that I can actually use to get a feel for the project.

    It looks like the cheap switches I used are problematic; they feel inconsistent, with some being clicky and others mushy. There might also be issues with the keycaps or the case contributing to this.

    My plan is to learn how to touch type on this keyboard. Perhaps I should put tactile marks on the keycaps to help with this.

View all 3 project logs

Enjoy this project?



River Wang wrote 07/12/2024 at 01:34 point

You might be interested in this pocket keyboard design contest.

  Are you sure? yes | no

Alex wrote 07/12/2024 at 05:12 point

Thank you. I'm in!

  Are you sure? yes | no

kelvinA wrote 10/05/2022 at 21:05 point

Has there been any additional progress in this project?

  Are you sure? yes | no

Alex wrote 10/15/2022 at 16:53 point

Unfortunately, no further progress has yet been made. But I plan to order a factory-made printed circuit board for the project.

  Are you sure? yes | no

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