OBJECTIVE //  Interested in making some large format art, I decided to employ the CNC precision of the modified 3d printer body that I had to create a pointillist style piece. Trying to find a reasonably inexpensive medium to work with that still felt robust, I landed on ceramic tiles and acrylic paint markers. The combination was key to ensure that there wasn’t too much resistance on when the pen made contact with the tiles and the built in spring loading of the pen tip.


……………(1) Old FDM body

……………(2) RUMBA ATmega 2560

……………(3) Ceramic Tiles

……………(4) Simplify3D

……………(5) Acrylic paint markers

……………(6) Java


Initially, I went down a more straight forward path that essentially just a dot pattern. I wrote a program that sliced an image into tiles, then processed each tile by reading the brightness at each potential point in the dot matrix. If it was below a certain threshold, then that spot would be marked with a dot. After this collection of dots was defined, each position was converted into GCode and saved out into separate files. I then used Simplify3D to stream this code to the RUMBA hardware and control the pen plotter.

After completing this piece, I decided to get more ambitious with coding. I had experimented a bit with mapping the pixel brightness to the intensity of each dot, by bleeding the pen for variable time periods. But the diameter didn’t seem to radiate quite proportionally to the time so the effect wasn’t terribly effective. I ultimately decided to have the machine draw small X’s who’s size mapped to the pixel brightness. It took a bit of testing to get a feel for how tight the grid should be and how much variation is needed between to the large and small X’s, but unfortunately, it also required completing the entire image to really understand how when it was going to show up.

The subject is a climber by the name of Alex Honnold. The image rendered reasonably well, but it is a little bit dark and the contrast is a little lower than intended. But it validated the effect and I think produced a pretty cool image.