My daughter likes buttons. She's learning letters. I was bored over winter break and had these parts laying around... so I built her a "Button Box" based around an Arduino. Open source, hackable ...

Capacitive touch sensors are entirely in the domain of DIY, requiring little more than a carefully-chosen conductive surface ...

Using a USB-C phone with Power Delivery is ideal here, as it allows the phone to be powered while also communicating with the Arduino over USB. The RemoteXY app is built specifically for this purpose.

Making a servo tester using an Attiny85 micro chip, Attiny45 also works for this project. This diy servo tester is as good as ...