How I made my drawing machine, and in the process made artists obsolete. When I first moved into my new studio, I had no important projects looming, and wasn't yet comfortable in the space. I built this "Drawing Machine" so that I could be productive, but not really. I would set it up, turn it on and then read Sculpture Magazine for a while as the machine did its jiggly business. This project was built using junk found around the studio for a cost of $0.00. It utilizes an old power drill with an offset cam in the chuck for motion.
Step 1: The Machine
Essentially, it's a power drill with an offset cam in the chuck clamped to a box. The cams were made using a hole saw on 1/8 inch copper sheet, with a thick copper stem hard soldered off center. A good deal of flexibility is available in this detail, as a lot of cam configurations can be used. The pics make it pretty clear how the rest of the thing is made. It's not rocket science, it's art.
Step 2: The Stylus
I hot-glued a bunch of pencil leads onto various objects: a super ball, the guts of a baseball, a tennis ball, some rawhide, and to other pencil leads. This is one of the factors that will determine what the finished drawing will look like.
Step 3: The Fence
In order to keep the stylus on the paper, a fence must be built on the face of the machine, I simply used some scrap cardboard and duct tape. Modifying this step will also greatly affect the end result. The fence probably shouldn't be too much bigger than the size of the paper, but can allow or restrict the motion of the stylus however you see fit.