Create Custom Gridfinity Boxes Using Images Of Tools

September 14, 2024 by Dave Rowntree 3 Comments

We love it when a community grabs hold of an idea and runs wild with it despite obvious practicality issues. Gridfinity by YouTuber [Zach Freedman] is one of those concepts. For the unaware, this is a simple storage system standard, defining boxes to hold your things. These boxes can be stacked and held in place in anything from a desk drawer to hanging off the side of a 3D printer. [Georgs Lazdāns] is one such Gridfinity user who wanted to create tool-specific holders without leaving the sofa. To do so, they made a web application using node.js and OpenCV to extract outlines for tools (or anything else) when photographed on a blank sheet of paper.

The OpenCV stack assumes that the object to be profiled will be placed on a uniformly colored paper with all parts of its outline visible. The first part of the stack uses a bilateral filter to denoise the image whilst keeping edge details.

Next, the image is converted to greyscale, blurred, and run through an adaptive threshold. This converts the image to monochrome, again preserving edge details. Finally, the Canny algorithm pulls out the paper contour. The object outline can be given an accurate scale with the paper contour and paper size specified. The second part of the process works similarly to extract the object outline. The second contour should follow the object pretty accurately. If it doesn’t, it can be manually tweaked in the editor. Once a contour is captured, it can be used to modify a blank Gridfinity base in the model editor.

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Bot Makes Etch A Sketch Art In One Continuous Line

September 28, 2018 by Dan Maloney 17 Comments

Introduced in 1960 for the princely sum of $2.99 ($25.00 today), Etch A Sketch was to become a standard issue item for the Baby Boomers’ toy box. As enchanting as the toy seems, it’s hard to see why it had staying power: it was hard for young fingers to twirl the knobs, diagonal lines and smooth curves required a concert pianist’s fine motor control, and whatever drawings we managed to make were erased at the slightest jostle of the tablet.

Intent on righting these wrongs, [Sunny Balasubramanian] not only motorized an Etch A Sketch, but he’s also given it a mind of its own in a way. For those unfamiliar with the toy, it’s basically a manual X-Y plotter that drags a stylus across the underside of a glass screen, scraping off a silver powder clinging to the glass to make dark lines. Replacing the knobs with steppers is straightforward, of course, but driving them is the trick. [Sunny] hooked his up to a Raspberry Pi and wrote some Python code to drive them. The Pi also accepts input image files and processes them for rendering through the plotter, first doing Canny edge detection in OpenCV, then plotting a single path through the largest collection of connected pixels in the image. From there it’s just a matter of spinning the motors to create surprisingly detailed images. Check out the short video below to see it in action.

It’s hardly the first automatic Etch A Sketch we’ve seen – here’s one that automates everything including the shake to erase the drawing. That one cheats a little though, in that it rasters across the screen like a CRT. We really like how this one just does a single path. Pretty clever.

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