This board acts as a touch board with a MPR121 for use along with my mouse core board this board has a place for female headers to be installed such that male headers on the core board can be attached and the board can be used as a mouse. You could design a larger enclosure for the board such that it is able to act as a traditional mouse but I opted to use it in my project as a levitated mouse with the help of elastic strings to allow it to reset between uses to help folks with muscle atrophy who may have a harder time using tradition mice that require lifting to reset the positioning.

I utilized conductive paint on my 3D printed part to allow the touch pads to be utilized but it did require the use of copper tape to properly get the sensitivity refined to a usable level. With that I'd suggest perhaps alternative means to trigger the buttons than my own design as it's definitely one of the areas that required a lot of rework to get to a perfect trigger state. Touching the board directly had no issues with sensitivity as the touch pads are setup fine it just is that additional element.

You can see my entire mouse video here:

The hardest part of this PCB is the MPR121 as it's hard to confirm while soldering that the leads under the module are properly soldered. To best accomplish the soldering needed here I found doing an initial solder paste on the leads followed by dragging the module over the leads worked well. I find that reworking components in this way is usually easier to position them so by dragging it back and forth it seated the module for me. I'd imagine with too much solder paste this could be an issue but in my case it worked out well luckily. Testing of each pad post soldering is important so utilize the test logic in the MPR121 library for further confirm this.

You'll need a few libraries to get this fully setup including the Adafruit Neopixel, the Adafruit MPR121, and the PMW3360 library linked in the mouse core board project page. Once setup though the logic for the mouse control is rather simple as it just polls the state each loop adjusting as needed.

If you'd like to use the associated 3D print files I used feel free to grab them from the associated hackster article that has more information. Otherwise feel free to utilize this however you wish!