Clunke Button

Assistive input device for interacting with adapted toys and tools.

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This is a low cost, printable AT button. It interfaces with any standard 3.5mm mono jack system, commonly found in support situations for people living with physical disabilities.


Clunke is a low cost button that can be used for toy adapting and similar functions, while also providing a clean and durable design.

AT buttons are a way for someone with a limited range of motion to control his or her environment at the same level as anyone else. These buttons can be used to adapt toys and home appliances such that they can be actuated with ease. Most AT buttons available are quite expensive, and are engineered to be used in high reliability situations. As a result there are home DIY projects to make cheaper buttons, but they often lack long term suitability and are thus more stop-gaps than replacements.


AT buttons are pricey. This project focuses on low cost, with a material price point of $10, while striving to provide a durable button that's fit for daily use.


This button's initial model was created as part of a team-based senior design course. We worked with a local organization, UCP and TASC of Huntsville, to design and construct an AT keyboard and AT button.

The senior design class ended with a second button design made, but not user tested. I now maintain the project and am working toward a third design revision and user testing.


The current button design requires a hobby level 3D printer and mechanical keyboard switches. See instructions below for build details.

Standard Tesselated Geometry - 689.37 kB - 08/23/2016 at 19:47


Standard Tesselated Geometry - 863.46 kB - 08/23/2016 at 19:47



Design file.

x-extension-fcstd - 349.61 kB - 08/23/2016 at 19:47



Design file.

x-extension-fcstd - 16.47 kB - 08/23/2016 at 19:47


Standard Tesselated Geometry - 3.40 kB - 08/23/2016 at 19:47


  • Because of course it uses an ESP8266

    Christopher Bero09/04/2017 at 07:12 0 comments

    This is a little off-track from the 3.5mm assistive button objective, but nevertheless I'd like to visit a brief moment in the project's journey when we decided that these AT buttons could also be hacker fodder:

    The circumstance leading up to this abomination is pretty clear: we had to give a presentation to an audience of a few dozen, and wanted them to be able to try the button for themselves. So here enters an ESP-01 and a small RC battery.

    The ESP firmware and companion desktop ticker are on github and pretty minimalistic.

    Amazingly, the ESP ticker had only a few milliseconds of delay between pressing the wireless button and updating the display. That left only battery life as a design consideration, which we thoroughly tested:

    (no lockout, so it just keeps spamming button presses)

    Again, amazingly, the button's diminutive battery held out of over an hour of this abuse! It's enough to make me wonder if a 802.11 wireless button could be used for serious applications. Bluetooth AT buttons are already available on the market, and we found a way to make our printed buttons operate the same way, so why stop there? With the increasing popularity of LAN and IOT based home automation, a web-connected button could become quite powerful in terms of accessibility. Just something to consider..

    The bluetooth buttons, also used during the presentation:

  • Designing for Warp

    Christopher Bero09/04/2017 at 06:46 0 comments

    The first couple of AT buttons we printed turned out well, but we quickly noticed a trend of warped bases where the edges of the PLA button tended to lift off of the printer's build plate.

    The curved bottom meant buttons would rock and make using them difficult. A solution was needed, and since I couldn't manage to tune the warping out of our printer's configuration, I turned to the button's 3D model.

    My first assumption was that warping was being caused by the large surface area of the button's base layer, so I made cavities in the first few layers to decrease the surface area:

    Results were disappointing. The buttons kept warping pretty much as they had prior to the modification.

    Luckily, I eventually came around to the notion that warping was a function of overall distance, not surface area. This meant we had to make the base layer contain less long segments:

    Success! The buttons started printing very flat:

    As you can see, the "fixed" buttons also started using a different color PLA filament. In retrospect, our small-lines solution may have been correlation instead of causation, so another pass of investigation is due at some point.

  • Why not Lasers?

    Christopher Bero09/04/2017 at 06:02 0 comments

    As part of the senior design project, we developed a prototype keyboard that didn't require fine motor control to use. It's construction involved both 3D printed mounts and laser cut plywood.

    So why didn't we use the laser cutter to make the adaptive button as well? Certainly the plywood would be cheaper, and even provide a more aesthetic result with some sanding and stain.

    Well, the main consideration is that the keyboard was an unvalidated concept, something we hoped would find traction with users. The buttons, however, already had a clear use case, market, and demand; these buttons needed a design with local, small scale production in mind.

    With the goal of making buttons easy to create, let's compare the laser and printer:

    • The laser cutter is somewhat more dangerous than a 3D printer, requiring more attention to safety during operation (see above).
    • The laser bed takes up 4 by 8 feet of floor space, whereas our 3D printer sits on a desk.
    • The laser creates fumes and needs industrial ventilation. The 3D printer isn't proven innocent in this category, but with certain filaments the air-based hazards can be considered mitigated.
    • Prices vary wildly among both 3D printers and laser cutters, but in our case we focused on making the button printable with sub $1000 FDM printers. Which meant that the $5000 laser cutter was much more expensive, again putting it out of reach for many DIY-ers who we want making these buttons.

    So the printer made an all-around better platform for creating small gadgets in local communities.

  • Picking a Button Size

    Christopher Bero09/04/2017 at 05:19 0 comments

    When UCP requested that our senior design team investigate cheaper AT buttons, we started with a commercial button as a reference:

    (representative image from

    They were pretty large, so we considered shrinking the design in order to save on 3D printer filament, and made some test prints to compare:

    Eventually we settled on a diameter of about 10cm, which provided a middle ground between surface area to hit and printable size:

    Were we to do it again, I'd want to focus more on obtaining many commercially available buttons and having ours match the apparent standards. This picking-values-out-of-the-air approach leads me to believe that our original design is less interchangeable than it could be.

View all 4 project logs

  • 1
    Step 1

    Making one button takes me about 8 hours of printing and 1 hour of assembly.

    • Print the button base, button hatch, and and key cap.
    • Solder the MX switch to the mono port with two pieces of wire, about 3 inches each.
    • Install the MX switch in the middle of the button base, and then run the mono jack to the port on the flat side. Screw the mono port's threads into the hole in the side of the button.
    • Jam the key cap onto the cherry MX switch. This can optionally be done with a light spring over the switch stem to adjust the force of the button.
    • Optionally glue or bolt (M3 bolts) the shelf liner to the bottom of the button to make a no-slip base!

    Can also optionally have superglue to hold things together.

View all instructions

Enjoy this project?



davedarko wrote 07/06/2017 at 20:56 point

this is also great for presenting projects stuff on cons / faires etc. - thank you for sharing :) 

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Christopher Bero wrote 07/07/2017 at 15:16 point

Good to know, thanks!

  Are you sure? yes | no

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