Instructables member JohnO3 calls his invention the "Skittle Pixel8r". It was a sophisticated programming and mechanical challenge, as the printer produces a specific image using pre-sorted Skittles. A motor moves the hopper along to drop in one Skittle at a time, slowly building the image from the bottom up.
You can find detailed instructions, including coding and wiring diagrams, at Instructables. But be warned:
It was supposed to be a weekend project but ended up taking a month to design and build.
That's the way projects usually work.