This is a list of the pen plotters I’ve found that can be built, roughly grouped by their kinematics. I’m considering building those in bold.
It’s possible to hook up a single belt in a clever way to move the pen in both the X and Y dimensions. They’re also called T-bots. This adds some complexity to the control software, but doesn’t require a stepper motor on the moving portion of the plotter.
[**PlottyBot**](<https://ben.akrin.com/?page_id=9650>) is a well-documented Raspberry Pi Zero-based plotter made with 3D printed parts and linear rods.
[SJSU XY-Plotter](<http://socialledge.com/sjsu/index.php/S18:_XY-Plotter>) was a final project for San Jose State University students and features a detailed write-up of the mechanism.
[DrawingBot](<https://www.thingiverse.com/thing:2058866>) uses 3D printed plastic and linear rods.
[DrawBot v1.1](<https://www.thingiverse.com/thing:2349232>) and the [Hackaday article](<https://hackaday.com/2018/10/15/the-3d-printed-plotter-you-didnt-know-you-needed/>) is a 3D-printed plotter that uses an Arduino Uno and CNC shield.
[4xiDraw](<https://www.instructables.com/4xiDraw/>) is a 3D printed AxiDraw knockoff with a nice guide.
[Crazy Engineer’s Drawing Robot](<https://arnabkumardas.com/cnc.html>) is made of wood blocks and metal, using an Ardunio running GRBL for control.
[ExtruDraw Extrusion-based Plotter](<https://www.thingiverse.com/thing:2994920>) is a 3D printed A2 or A3 format plotter mounted on an MDF baseboard and uses the AxiDraw’s EiBotBoard.
[The AxiDraw pen plotter](<https://mattwidmann.net/notes/the-axidraw-pen-plotter>) was responsible for a resurgence in plotter art and is a commercial product with a large community. The MiniKit 2 is a kit that builds an A6 version of the plotter and does not require fabricating any parts.
Some of the less-polished plotters are below:
[Drawbot plotter](<https://grabcad.com/library/drawbot-plotter-1>) is a 3D printed plotter on 6 linear rods.
The EleksDraw is an AxiDraw knockoff that [comes as a kit](<https://www.basjacobs.com/post/2018-06-28-pen-plotter/>).
[BOTomazov](<https://maxoffsky.com/research-progress/building-project-botomazov/>) is Maks Surguy’s squiggle plotter.
[The Plot Thickens](<https://feralresearch.org/the-plot-thickens/>) describes the assembly of an AliExpress pen plotter.
Using two belts for XY motion is a straightforward system that’s suitable for smaller plotters.
[**midTbot**](<https://www.buildlog.net/blog/2017/10/the-midtbot-a-new-flavor-of-h-bot/>) is a very compact design where both steppers are mounted over the linear bearings. In 2020, Ben Congdon wrote about [Building a DIY Pen Plotter: midTbot](<https://benjamincongdon.me/blog/2020/07/12/Building-a-DIY-Pen-Plotter-midTbot/>).
[**Andrew Sleigh’s pen plotter**](<https://github.com/andrewsleigh/plotter>), now at version 3, is a 3D printed plotter with a V-slot X axis.