Etch-A-Snap is (probably) the worlds first Etch-A-Sketch Camera. Powered by a Raspberry Pi Zero (or Zero W) it snaps photos just like any other camera, but outputs them by drawing to an Pocket Etch-A-Sketch screen. Quite slowly.
Photos are processed down to 100x60 pixel 1-bit (black & white) line drawings using Pillow and OpenCV and then translated into plotter commands by building a network graph representation with networkx. The Etch-A-Sketch wheels are driven by two 5V stepper motors mounted into a custom 3D printed frame. The Etch-A-Snap is entirely portable and powered by 4xAA batteries & 3x18650 LiPo cells.
The developing time for a photo is approximately 15 minutes - 1 hour depending on complexity1.
The first video below shows the process of taking a photo with the Etch-A-Snap, including the initial drawing of the image on the screen. The second clip is a timelapse showing the drawing of the resulting picture.
Keep scrolling for some more examples.
Camera Examples
These shots were taken live using the Etch-A-Snap — a single shot was taken and immediately drawn to the screen. The drawing process was captured using a timelapse camera.
Outdoor street view, showing the Etch-A-Snap struggling a bit on building details.
In early tests the Etch-A-Snap ran at 2 pixels per second, but now achieves a lightning fast 20 pixels per second.
Image examples
The Etch-A-Snap can also draw a picture from any image type supported by Pillow using the draw.py utility. Using this script the Etch-A-Snap crops, resizes and processes the images the exact same way as from the camera, but you can be a bit more selective with the image and increase the chances of getting something half decent out.
Etch-A-Sketch logo generated from a monochrome PNG.
The Queen. There is no route-optimisation (travelling salesman) at work when drawing, aside from adding weight to previously draw areas to encourage avoiding them in future. This picture of the Queen shows some serious back-tracking over the hair/top right corner.
Django Wagner. Het is weer weekend. This picture produces a poorly connected network around the face, which Etch-A-Snap deals with by adding a number of linker lines (shown in red). These links are optional additions, which can be used to shortcut while drawing but omitted if not needed — the right ear shows an example of an unused linker.
How does it work?
If you're interested in how the Etch-A-Snap works, or want to build one yourself, take a look at the separate parts of the write-up — Build, Processing, Drawing and Plotter.
The following files and resources are also available —
- The full code is available on Github along with a Jupyter notebook which details (and allows you to) experiment with the image processing and graph generation.
- You can download the STL files for 3D printing, or edit the model on TinkerCad directly.
- The circuit Fritzing file is also available.
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It's quicker than film! ↩
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