This giant robot uses a v-plotter design to move a large drawing head containing 8 spray paint cans around the side of a wall. It produces some of the largest murals with no human effort. It doesn't look like it's terrible high resolution but you can work around that with just making everything bigger.

Here is a short clip of it in action with it's creator, Janwillem te Voortwis .

There is a very detailed writeup as the project was apparently a graduation project for the inventor. Well done and hopefully he passed with flying colors.