- [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.
- [HP Pen Plotters](https://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](https://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.
- [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.
- [@beardicus/line-us](https://github.com/beardicus/line-us) – JavaScript library for controlling the [Line-us](https://www.line-us.com) machine from Node or the browser.
- [GRBL-Plotter](https://github.com/svenhb/GRBL-Plotter) – Plotter-optimized Windows GUI for grbl controller with SVG and DXF import, and flexible pen up/down control.
- [saxi](https://github.com/nornagon/saxi) – Driver and library for the AxiDraw. Uses constant-acceleration motion planning and automatically resizes to paper.
- [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".
- [penkit-optimize](https://github.com/paulgb/penkit/tree/master/optimizer) – An SVG optimizer that uses a vehicle routing solver to minimize plot time.
- [svg-crowbar](https://github.com/NYTimes/svg-crowbar) – Chrome-only bookmarklet for extracting SVG from an HTML document.
- [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.
- [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.
