This robot will draw out any small monochrome bitmap onto poster paper. It can mark out the individual pixels just as a printer might. It works best with strings of characters.
This is a moderately difficult project which requires about $50 in parts and basic electronic skills (This doesn't include an iRobot create,Command Module and old Inkjet printer) . You should be able to read a schematic and make a basic prototype or bread board. Some familiarity with C or C++ is handy too.
I recommend that you read through the entire Instructable before beginning your project. It's important that you get the bigger picture because the process will vary depending on your materials.
An Old inkjet printer
An iRobot Create and Command module
Electronic prototype board or bread board
Several rubber bands
Two 9-pin serial cables with at least one male end
4 PC-Mount DPDT 5v DC relays rated at least 1A
4 2n222 transistors
4 1k 1/4 watt resistors
some wire to make jumpers with (unbraided)
~3' of 1/8" Bass wood
Butcher paper (get at least 20')
Voltage regulators (values vary)
White acrylic paint (optional)
Box Cutter or Exacto knife
Drill and bit set
Hot melt glue gun