I decided to make this robot because I've never had very neat handwriting, so making large letters has always been difficult. When I was on Student Council in high school, I always got marked down for posters that weren't "neat" enough. Like any nerd, I figured "If I can't do it, I'll make a robot to do it for me."
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
You need two parts from the printer: the carriage and the paper advancer
The carriage is what the ink cartridges slide back and forth on. It's a metal rack with a motor, a belt, a plastic strip, a white ribbon cable and the actual print-carriage (usually black) where the ink cartridges sit.
You can go ahead and remove the white ribbon, the ink cartridges and the clear plastic strip with the black marks.
The paper advancer is a little harder to remove. It's usually deep in the printer and is attached to a lot of other things.
From the advancer, the parts we want are: the motor, its gear train, its axle (with the little foam wheels) and any bearings it has.
Try to keep these parts in working condition.
We're going to cut the paper advancer axle with a hack saw just outside the second bearing. This will be our medium lowerer which is a not-too-fancy way of saying it the thing that is going to move the marker to and from the paper.