Part of Core77's Greener Gadget competition, instructions are pretty simple:
1. Insert a paper in the middle of the printer
2. Put the coffee or tea dregs into the ink case on the top of the printer
3. Move the ink case left and right as you draw on a paper
4. When the print finishes, pull out the paper from the printer and wash the ink case
Local Starbucks could give Kinko's a run for their money!