1 Resistor (this one is optional, any between 110 to 330 ohm will do).1 Arduino Leonardo (or any Arduino with usb interface).In my case, I use it with coding software to have an easy and fun shortcut to copy, paste, duplicate line, save, capture screen and open a couple of apps. You will create a panel with different buttons, each one will do an action in your computer (Mac or Pc) by emulating keyboard shortcuts or commands. This is a pretty simple and fun project with Arduino which is an ideal option for your first interaction with Arduino.