Paul Butler organizes the [Plotter Twitter Postcard Exchange](https://paulbutler.org/2022/generalizing-secret-santa-with-integer-programming-in-julia/) for fans of plotter vector art (although it's not exclusively on that site anymore since many of us have left). Participants sign up for sending some number of post cards and in turn receive an equal number from some of the other participants. If you like these, you can follow me on Mastodon as [@th@v.st](https://v.st/@th) and see other `#plotterart` that I post there. ## 2024  The plan for 2024 was another animation of a 3D object created in [OpenSCAD](https://openscad.org/) and rendered by my [plotter.vision](https://plotter.vision) STL to SVG tool, with each frame plotted using a different pen. It's a bit chaotic due to the flashing colors as well as bad photography of the cards.  The plotter is the same AxiDraw SE/A3, now with a Pi Zero-W attached and running [saxi](https://github.com/nornagon/saxi) to provide a web front-end for drag-n-drop plotting. I also wrote instructions for [powering the Pi via USB-OTG so that it can share power with the plotter](https://github.com/nornagon/saxi/blob/main/README.md#raspberry-pi-zero-otg).  ``` // https://v.st/ptpx#2024 module ptpx(){ for(i=[1:5]) hull() for(a=[i,i+1]) rotate([a*72]) translate([0,20]) sphere($fn=4); } for(i=[1:5]) rotate([(i+0.5)*72]) rotate([0,116]) ptpx(); ptpx(); ``` The code for the tangled pentagons is quite short, so I included it on the back of the cards for each recipient. There is an [online OpenSCAD render](https://ochafik.com/openscad2/#H4sIAAAAAAAAA3WRTW+DMAyG/wrKdoCVdlCtq8bUwy47T9qRcvBCgEghRvnoF+K/LymDbofd7Mevnfh1TzpQ0GqS9QSo4Qf2AaYhGXnsBJxrhVaWK02hJDHRaBVlTpr3rus/FUVpmDSu2GJpBQs6053CqN/LIKhQhXyXp9mmiILGChFGHo8F2OU85ou0+GFBoNCAYWEOD9v1jRoFUotrIYnXya2gu4YpFt5XcvcUve7lsJe/H/SyaWLIF8lqE81zJ57Eafo8ovHbbswckKGIScXAWHV1gbQgeYXCb12BNkuqaxcKuJyXVnKULgGtedu5QDFZMrWkKFBpUkzgHVUL3qxafDkVO3WozB84xOTA2dEfyHmN1vjIWcu8w1YY7ttKblCRzCjLRjmbM2q1wZZfPKlAaDb4GwkvJ3fVS7ldU3/bBo9vJ7/W2OXzzwZKPM5IYK2nEcM3rAA8oTgCAAA=) if you want to play with it, or you can run it locally.  Unfortunately the different inks turned out to be very very chaotic, rather than good looking. It was, however, a chance to test all of my pens and find some favorites! The MVP's from this year's #PTPX are the Pentel "Dual Metallic K110", the Faber-Castell Metallics "Ice Ice Blue", the ColorMaster fine nib silver, and the returning favorite, the Pilot "G-TEC-C4" ## 2023  This year was about experimenting with some different pens to try out gels versus metalics versus brushes. So everyone gets a unique piece! Most of the cards are [Truchet Tiles](https://en.wikipedia.org/wiki/Truchet_tiles) this year and wrote an [SVG tile generator](https://osresearch.github.io/truchet/) to try out different variations as I experimented with the design. Every card is another tweak to the code, testing out different amounts of wiggle or having the roundyness disperse cross the plot, so it isn't possible to regenerate the existing ones. I also thought about making some mazes and even [wrote a generator](https://osresearch.github.io/truchet/maze.html), although it wasn't a fun as I had hoped. ## 2022  For 2022 I used the stop-motion animation idea again, this time with a "knot" generated by my [customizable mobius torus generator](https://www.thingiverse.com/thing:5189077) and rendered with my STL-to-SVG tool, [plotter.vision](https://plotter.vision).  The other fun change this year was using "[postzegelcodes (NL)](https://nl.wikipedia.org/wiki/Postzegelcode)", a hand-written form of postage offered by PostNL. Rather than going out for stamps or printing postage at home, they give you a nine alphanumeric character code that you write as a 3x3 grid. ## 2021  This year was a good test of my [plotter.vision](https://plotter.vision) tool's ability to do coplanar surface detection and also burned through the AxiDraw's mini servo drawing all the small boxes... The shape is a [Menger sponge](https://en.wikipedia.org/wiki/Menger_sponge), a type of fractal. ## 2020  This was the first year I particpated in #ptpx and had just finished the [plotter.vision](https://plotter.vision) tool's "anaglyph" support for red-blue 3D glasses. The two figures are the usual Stanford Bunny, reduced to a low-poly form, and the [Simplified Holiday Christmas Deer (lowpoly remix) by mitrasmit](https://www.thingiverse.com/thing:1222937).