Build your own Makey Makey
The Makey Makey is a great board to quickly build interface devices. It plugs into a computer and gets recognized as a keyboard and mouse and allows you to easily add buttons and switches to your setup. As it works on conductivity you can change all kinds of objects (such as bananas) into buttons.
However, the Makey Makey is quite expensive, can't be easily modified and isn't always as easily available. Luckily you can build a very similar input device using a pico. After following the steps below the boards will get recognized as a HID (keyboard, mouse, gamepad) by any computer and OS (Mac/Win/Linux).
This process consists of the following steps:
Adafruit Circuitpython library bundle: https://circuitpython.org/libraries
Adafruit HID library documentation: https://docs.circuitpython.org/projects/hid/en/latest/