* [AxiDraw](https://shop.evilmadscientist.com/productsmenu/846) – Pen plotter from [Evil Mad Scientist](https://www.evilmadscientist.com/), very popular on [#plottertwitter](https://twitter.com/hashtag/plottertwitter).
* [Line-us](https://www.line-us.com/) – A cute little kickstarted robotic drawing arm.
* [WaterColorBot](https://watercolorbot.com/) – XY art robot and software to plot with watercolor paints.
* [EggBot](https://egg-bot.com/) – Pen plotter for egg-shaped and spherical objects.
* [HP Pen Plotters](http://www.hpmuseum.net/exhibit.php?class=4&cat=24) – Vintage desktop and floor-standing pen plotters from the creator of the HPGL standard. Model 7475A is very common and can usually be found on eBay.
* [grblShield](https://github.com/synthetos/grblShield) – All the stepper motor control hardware needed to turn an [Arduino](https://www.arduino.cc/) into a G-code-based motion controller using the grbl firmware. ([adafruit](https://www.adafruit.com/product/1750))
* [TinyG](https://github.com/synthetos/TinyG/) – More featureful and robust 6-axis G-code-based motion control hardware. ([adafruit](https://www.adafruit.com/product/1749))
* [Arduino CNC Shield](https://blog.protoneer.co.nz/arduino-cnc-shield/) – Grbl-compatible stepper motor control shield for Arduino, similar to the [grblShield](https://github.com/synthetos/grblShield).
* [Raspberry Pi CNC Hat](https://wiki.protoneer.co.nz/Raspberry_Pi_CNC) – Raspberry Pi add-on board w/ stepper controllers and a microcontroller running grbl. Interfaces with the Pi's serial pins
* [WiFi232](http://biosrhythm.com/?page_id=1453) – Wifi to RS-232 serial via a DB25 plug. Control your serial plotter wirelessly.
* [Plotter Cable Pinout](http://sites.music.columbia.edu/cmc/chiplotle/plotter_cable.pdf) (PDF) – Schematic for a plotter cable that will work for most HP and Roland plotters. Search eBay or Amazon for `DB9 to DB25 Serial Null Modem Cable` or similar to find them for sale.
* [Sharpie Fine Point Plotter Adapter](https://www.thingiverse.com/thing:229982) – 3d-printed adapter to fit a standard Sharpie in an HP-GL plotter.
* [Parametric 3d-Printable Plotter Pen Adapter](https://openjscad.org/#https://gist.githubusercontent.com/beardicus/d668c0f6b96be53d16dc/raw/plotter-pen-adapter.jscad) – Adjustable model to print adapters for various pens.
* [Plotter Pen STL Models](https://www.thingiverse.com/thing:227985) – Accurate STL models of both short and long standard plotter pens.
* [Pens for AxiDraw](https://wiki.evilmadscientist.com/Pens_for_AxiDraw) – List of pens suitable for general plotter abuse.
* [Pens for EggBot](https://wiki.evilmadscientist.com/Pen_choices) – Egg- and glass-focused pen recommendations but still generally applicable information.
* [Chiplotle](https://github.com/drepetto/chiplotle) ([web site](http://chiplotle.org/)) – Python library for generating HPGL and interfacing with serial plotters.
* [HPGL Reference Guide](http://www.isoplotec.co.jp/HPGL/eHPGL.htm) – HTML-based HPGL Reference.
* [HP 7475A Interfacing and Programming Manual](https://archive.org/details/HP7475AInterfacingandProgrammingManual) – Scanned PDF manual that contains a full HPGL reference.
* [djipco/hpgl](https://github.com/djipco/hpgl) – A Node.js library to communicate with HPGL-compatible plotters and printers.
* [hp2xx](https://www.gnu.org/software/hp2xx/) – GNU tool to convert HPGL into other vector and raster formats. Can also be used as a previewing in X11.
* [vec](https://github.com/anachrocomputer/vec) – Example C code for generating HPGL, with a turtle graphics interface.
* [d3-hpgl](https://github.com/aubergene/d3-hpgl) - An adapter for the HTML Canvas API so you can output HPGL using the popular [D3](https://d3js.org/) library.
G-code is a text-based standard for controlling CNC machines. Though it was designed for industrial machines, its use in many hobbyist 3d printer firmwares has made it ubiquitous in small-scale DIY projects as well.
* [axidraw](https://github.com/evil-mad/axidraw) – Official AxiDraw extensions for Inkscape.
* [axi](https://github.com/fogleman/axi) – Unofficial Python library for the AxiDraw v3.
* [xy](https://github.com/fogleman/xy) – Utilities for the Makeblock XY Plotter Robot Kit.
* [LaserGRBL](https://github.com/arkypita/LaserGRBL) – Laser-optimized Windows GUI for grbl controllers. Could be repurposed for DIY pen plotters that use a solenoid for pen up/down movements.
* [Line-us Inkscape Plugin](https://github.com/Line-us/Inkscape-Plugin) – Sends drawings to the [Line-us plotter](https://www.line-us.com/) directly from Inkscape.
* [Line-us API Examples](https://github.com/Line-us/Line-us-Programming) – Example code for the [Line-us](https://www.line-us.com/) plotter's G-code-based API.
* [PenPlotter](https://github.com/RickMcConney/PenPlotter) – Polargraph controller that uses repetier firmware.
* [Makelangelo-firmware](https://github.com/MarginallyClever/Makelangelo-firmware) – Firmware for the Makelangelo polargraph robot.
* [RoboPaint](https://github.com/evil-mad/robopaint) – Software for the WaterColorBot.
* [AxiTurtle](https://github.com/ralphcrutzen/AxiTurtle) – Turtle graphics for AxiDraw in Processing.
* [SquiggleDraw](https://github.com/gwygonik/SquiggleDraw/commits/master) – "SquiggleDraw will create a SVG file from an image, using the brightness to change the amplitude of sine waves".
* [svgurt](http://svgurt.com/) – Web-based PNG to SVG creative noodler.
* [maptrace](https://github.com/mzucker/maptrace) – Produce watertight polygonal vector maps by tracing raster images.
* [venation](https://github.com/Shornone/venation) – Modeling and visualization of leaf venation patterns.
* [Drawbot_image_to_gcode_v2](https://github.com/Scott-Cooper/Drawbot_image_to_gcode_v2) – Creates G-code for use on drawbots.
* [blackstripes](https://github.com/fullscreennl/blackstripes-python-extensions) - Turns a PNG image into a SVG line drawing.
* [Ribbon](https://github.com/fogleman/ribbon) – Ribbon diagrams of proteins in written in Go.
* [penplot](https://github.com/mattdesl/penplot) – A development environment for plotter art in JavaScript.
* [penkit](https://github.com/paulgb/penkit) – A Python library for creating line-based SVG graphics.
* [generativeExamples](https://github.com/digitalcoleman/generativeExamples) – Example Processing code that generates plottable PDFs.
* [Let's make map](http://svg-exporter.netlify.com) – Web-based tool to export an SVG map from Mapzen tiles.
* [SuperformulaSVG for web](https://jasonwebb.github.io/SuperformulaSVG-for-web/) – A generative line art web app.
* [scribbleplot](https://github.com/bleeptrack/scribbleplot) – Scribbly image transformations in Processing.
* [svgsort](https://github.com/inconvergent/svgsort) – Path planning for plotting SVG files, reduces time spent moving with the pen up.
* [svgo](https://github.com/svg/svgo) – Node.js-based tool for optimizing SVG files.
* [Polargraph Optimizer](https://github.com/ezheidtmann/polargraph-optimizer) - Optimize drawing plan for a polargraph.
* [penkit-optimize](https://github.com/paulgb/penkit/tree/master/optimizer) – An SVG optimizer that uses a vehicle routing solver to minimize plot time.
* [Summary of single line fonts](http://imajeenyus.com/computer/20150110_single_line_fonts/index.shtml) – Good information and links to other resources and fonts.
* [Hershey Vector Font](http://paulbourke.net/dataformats/hershey/) – `.fnt` format of vector fonts from the 60s. Includes a good overview of the original data format of the fonts.
* [hershey-fonts](https://github.com/kamalmostafa/hershey-fonts) – C library and original font data for the Hershey fonts.
* [OneLineFonts.com](http://www.onelinefonts.com/) – Commercial site with some single-line fonts available for purchase.
* [An Intro to Pen Plotters](http://www.tobiastoft.com/posts/an-intro-to-pen-plotters) – Good info on getting started with old HPGL plotters.
* [1980s pen plotters of the future](https://notes.variogr.am/2012/08/12/1980s-pen-plotters-of-the-future/) – Another intro to vintage pen plotters.
* [Pen Plotter Programming: The Basics](https://medium.com/@fogleman/pen-plotter-programming-the-basics-ec0407ab5929) – Some basics of programming vector paths, including sorting, joining, and simplifying.
* [Roland DG DXY-990](https://hackaday.io/project/12276-roland-dg-dxy-990) – Quickstart guide for a Roland flatbed plotter.
* [The Cohen-Sutherland Line Clipping Algorithm](https://sighack.com/post/cohen-sutherland-line-clipping-algorithm) – Detailed explanation and examples of an interesting algorithm.
* [Vera Molnár](https://www.surfacemag.com/articles/vera-molnar-in-thinking-machines-at-moma/) – OG plotter artist.
* [The Recode Project](http://recodeproject.com/) – "The ReCode Project is a community-driven effort to preserve computer art by translating it into a modern programming language".
* [Hektor](http://juerglehni.com/works/hektor) – The original cable-based drawbot from 2002.
* [Pen Plotter Art & Algorithms Part I](https://mattdesl.svbtle.com/pen-plotter-1) and [II](https://mattdesl.svbtle.com/pen-plotter-1) – A two-part intro to creating generative graphics for plotting.
* [Surface Projection](https://bitaesthetics.com/posts/surface-projection.html) and [Fractal Generation with L-Systems](https://bitaesthetics.com/posts/fractal-generation-with-l-systems.html) – Some techniques for creating line graphics suitable for plotting.
* [Pen Plotter Art & Algorithms](https://mattdesl.svbtle.com/pen-plotter-1) – Introduction to plotters, AxiDraw, walkthrough of the `penplot` library.
* [Surface Projection](https://bitaesthetics.com/posts/surface-projection.html) – Deep dive into surface projection and hidden line removal using Python and penplot.
* [Introduction to TSP art](https://wiki.evilmadscientist.com/TSP_art) – Resources for traveling salesman problem (single path) art.
* [Hidden wireframe removal](https://trmm.net/Hidden_Wireframe) – Discussion and links to code for wireframe removal of STL files.
* [Chiplotle-discuss](https://lists.columbia.edu/mailman/listinfo/chiplotle-discuss) – Fairly inactive mailing list for the Chiplotle HPGL Python library with some general plotter talk.
