How to send keyboard keypresses/words from an Arduino UNO R3

I was inspired by The AWESOME Button: A Made-to-Measure USB Input Device - Make: to make a keyboard input device with an arduino but without having to use processing or any other programs so it would be able to plug and play for any computer. My main use for this would be to use it as a Ctrl + V button so when im writing arduino codes with many, many digitalWrite's I don't have to keep re-adjusting my hand to the left. One more thing,I was thinking of having a single foot pedal button to control this.

At the core of The AWESOME Button is the Teensy USB, a really sweet* microcontroller that has the ability to act like a USB mouse or keyboard right out of the box.

Making an Arduino (UNO or Mega2560) act like a USB mouse or keyboard is possible, but not right out of the box.

My main use for this would be to use it as a Ctrl + V button so when im writing arduino codes with many, many digitalWrite's I don't have to keep re-adjusting my hand to the left.

Perhaps instead of adding new hardware, you should learn better programming techniques.