CAD

One concern with CAD is a fundamental aspect of their architecture: How are curves, arcs and circles handled? All- too-many programs take the expedient route of representing them as as polygons or polylines. Academic paper discussing this G codes for the specification of Pythagorean-hodograph tool paths.

Please note that it is possible to use pretty much any vector drawing program for design, esp. if one limits oneself to 2D (one interesting example of this is the use of a JavaScript to generate G-Code from vectors w/in the page layout program InDesign (see IterativePathCuts (unfortunately limited to straight lines) at Silicon Publishing: Resources, forum discussion)). The 2D drawing programs listed below were chosen for their having especial support in the form of features or plug-ins to support CAM.

This page focuses on interactive programs, manipulation of numbers/parameters and code is covered on the Programming page.

A note on curve approximation: The trivial case with four cubic beziers (one on each quadrant) has very low maximum error, IIRC on the order of 0.1% of the circle radius.

Origin point This is different from most drawing and CAD programs: https://bugs.launchpad.net/inkscape/+bug/170049 as discussed here: http://www.shapeoko.com/forum/viewtopic.php?f=6&t=5102&p=37166#p37166

A note on vector drawing: Vector drawing is like to drafting with rules, triangles, compasses and a French curve, while pixel editing is more akin to colouring in spaces on a grid. Vector drawing uses lines (a straight path between two "nodes" which are x,y coordinates, one is the beginning, the other the ending), regular geometric forms (defined by nodes which denote each point at which lines meet), arcs and circles (defined by the central point of rotation and the radius therefrom) and Bézier curves (a mathematical description of an arbitrary curve which has four "nodes", one on-the-path, two off-the-path and one on-the-path) to allow it to express pretty much any shape or form.

A game to learn about forming such curves: http://bezier.method.ac/#

A Primer on Bézier Curves

Often, clip art will be done in stroked lines which are not suited to most CAM programs --- the solution is expanding the strokes and unioning them: https://community.carbide3d.com/t/converting-line-art-for-drawing/9493

A note on units: Most CAD programs store drawings in generic units, rather than a specific measure. It is important to know what unit was used when a drawing was created so as to be able to import it at the right size. Forum discussion.

It is also of course, straight-forward to work directly in G-Code, accomplishing Design and CAM in a single step using programs which provide integrated text editing such as NC Plot and NC Corrector (the latter is listed on the Previewing G-Code page. A tutorial is listed on the CAM page. Unfortunately, Grbl’s implementation of G-code leaves out variables and looping, so is not suited for this --- there is at least one pre-processor, G-sharp which affords support for these features, instantiating them as simpler G-code, bCNC supports this.

Note: A number of programs listed on the CAM page include design features for such specialized things as PCBs, Thread and Fret cutting and Gears.

https://www.sculpteo.com/blog/2016/12/14/top-8-cad-software-for-kids/

See also


 * https://wayofwood.com/free-cad-software-for-makers/
 * Why We Need Professional-Level Open Source CAD
 * CAD/CAM Wish List
 * https://directory.fsf.org/wiki/Category/Business/cad
 * https://www.reddit.com/r/cad/wiki/index
 * http://m.slashdot.org/story/183415
 * https://www.reddit.com/r/3Dprinting/comments/3odhn9/im_thinking_about_learn_some_3d_modelling_what/cvwfj0z
 * https://www.matterhackers.com/articles/finding-the-right-3d-modeling-software-for-you
 * https://all3dp.com/1/best-free-cad-software-2d-3d-cad-programs-design/
 * http://www.pilot3d.com/NurbSecrets.htm
 * https://opensource.com/article/19/2/3d-printing-course

The Failed Promise of Parametric CAD, a series of articles by Evan Yares:
 * From the Beginning
 * The Problem is Editing
 * The Direct Solution
 * Going Horizontal
 * A Resilient Modeling Strategy
 * Viable Solution

http://mikeestee.com/2012/03/open-source-parametric-cad/

History: http://www.cadhistory.net/ and https://www.scratchapixel.com/lessons/advanced-rendering/bezier-curve-rendering-utah-teapot

File formats

https://en.wikipedia.org/wiki/Comparison_of_computer-aided_design_editors

Page with table listing many opensource CAD apps: https://sites.google.com/site/lagadoacademy/miscellaneous-projects/free-cad-software---overview --- includes columns for OS compatibility, incl. whether or no an app will run in Linux using WINE.

Integrated CAD/CAM

 * Carbide Create --- runs on Mac OS X and Windows, imports DXFs and SVGs, CAD/CAM functionality, and supports V-carving.
 * http://sourceforge.net/projects/technecadcam/ --- notable for outputting Shopbot instructions as well as G-Code.

2D
Forum Poll

AutoCAD clones:

http://blog.dreamcss.com/design-tool/10-useful-free-alternative-to-autocad/


 * Siemens Free 2D (listed above)
 * http://www.cadlogic.com/cad-software/draft-it/default2.asp

Note that Draftsight is no longer freely available.

DWG/DXF Viewer
Autodesk DWG TrueView™

Tracing
Tracing is a useful option for some projects. Most vector drawing programs have an option for this (one option is to place the image on the desktop or in a window beneath the CAD tool, then make that window transparent), or one can use a specialized tool. One such: http://www.kvec.de/english/index.htm Discussion: https://www.reddit.com/r/CNC/comments/47fqeh/best_raster_img_to_scalable_vector_programs/

Opensource tracing: http://potrace.sourceforge.net/ --- web interface: http://www.vectorization.org/

Webservice for tracing: https://convertio.co/jpg-svg/ or http://online-convert.com/

Mechanism for tracing / digitizing existing designs / templates: http://www.logicgroup.com/LogicTraceCncDxf.html

https://www.vectorization.org/

https://svgcreator.com/

http://www.z3d.jp/lab/tracetool.php

https://picsvg.com/

Extrusion
http://www.extrudy.net/ --- create simple, printable 3D objects such as coins, pendants, earrings or medals. Youtube Reddit

http://www.selva3d.com/

https://github.com/jeremysimmons/heightmap2stl-gui/releases/tag/v1.2

Fonts
In many instances a single-line font is a desirable option for CNC. The Hershey Fonts in Inkscape are one notable option. See the article: https://lwn.net/Articles/654819/

Lengthy article and list of options at: http://imajeenyus.com/computer/20150110_single_line_fonts/index.shtml

https://nationalparktypeface.com/

Images
https://www.evilmadscientist.com/2012/stipplegen2/ Tsp_sld

http://www.aggregate.org/MAKE/TRACE2SCAD/

More CAM, but http://rastercarve.live/

https://imagetostl.com/

3D
c.f., Programming: 3D Modeling Libraries and Languages for tools such as OpenSCAD.

Merging the boundaries between 2D and 3D, CAD and CAM, there's http://www.flatfab.com/ Fabrication Design Software that helps you design and fabricate 3D objects. Ideate and draw in 2D, fabricate in 3D.

Forum Poll

https://callmevice.com/2016/05/07/free-paid-3d-modeling-tools-for-3d-printing/


 * CollabCAD --- 3D CAD/CAM Software system for collaborative design & development of Industrial Designs. Written in Java, available for Linux and Windows, reads XML, STEP, IGES, and VRML.
 * Varkon --- parametric 2D/3D CAD, modeling and application development tool for engineering, design, architecture, etc. does 2D drafting, 2D and 3D modeling, sculptured surface modeling, and animations. Includes a 6-minute tutorial.

Anim8or --- Windows 3D modelling tool able to import and modify .3DS files

http://www.3dvia.com/products/3dvia-shape/

https://www.bricsys.com/en-intl/shape/ --- used in architecture.

http://web-cad.org/ --- https://github.com/xibyte/jsketcher https://hackaday.com/2016/12/24/open-source-parametric-cad-in-your-browser/

http://stephaneginier.com/sculptgl/

https://mecsoft.com/visualcad/

Android app for Mattel's Thingmaker: https://play.google.com/store/apps/details?id=com.mattel.thingmakerdesign

Apple Mac App Store: Strata Design 3D SE 7 --- https://www.strata.com/design-3d-se/

https://www.bricsys.com/en-intl/shape/ --- available for Linux, Mac OS X, Windows https://www.cadnauseam.com/2018/01/23/bricscad-shape-can-a-free-dwg-product-be-a-bim-game-changer/ https://blog.bricsys.com/introducing-bricscad-shape/

Interesting post on efficiency: http://community.carbide3d.com/t/how-to-make-your-stl-not-take-3-days-to-calculate-tool-paths-for/169

http://www.ptc.com/cad/elements-direct/modeling/express --- Creo Elements/Direct Modeling Express 6.0 is a free version of Creo Elements/Direct Modeling 19.0 limited to assemblies with up to 60 unique parts.

As an alternative to OpenSCAD see http://www.plasm.net/ or the nascent http://makertron.io/

Previewers
https://papas-best.com/stlviewer_en

https://all3dp.com/free-stl-file-viewer-to-open-view-stl-files/

iPad STL viewer: 3D Push Source on Github

Online modelers
Some may find OnShape sufficiently free to consider it: https://www.onshape.com/ or

https://www.vectary.com/

http://edges.io/ --- noted as working well w/ a stylus.

https://clara.io/

https://app.sketchup.com/app?hl=en

3Dtin now refreshes to: https://www.tinkercad.com/

Image Depth Maps

 * https://github.com/DEF7/TGA2STL
 * height map to STL
 * https://github.com/anoved/hmstl
 * https://github.com/jeremysimmons/heightmap2stl-gui --- converts a pixel image into a 3D STL file.
 * http://3dp.rocks/lithophane/

https://www.selva3d.com/ --- converts images into depth maps which are then integrated into a library of 3D models at "standard accuracy" (better quality modeling is a paid option).

Apparently Microsoft's 3D Builder can create depth / height maps from pixel images as well: Commercial Software

Bricks

 * https://all3dp.com/3d-slash-review/ review

Further things to add
http://prisma3d.net/ --- Android

3D CAD to add

 * HyperFun
 * PLaSM

2D CAD to add

 * LibreDWG
 * OpenDWG
 * Archimedes http://archimedescad.github.io/Archimedes/ https://sourceforge.net/projects/arquimedes/ --- https://www.osalt.com/archimedes
 * SAMoCAD --- http://vvs1864.github.io/samocad/en_index.html
 * SagCAD --- Japanese CAD program
 * The Piglet Drawing Editor --- 2-D engineering drawing editor that supports hierarchical object description, inspired by Hewlett-Packard's proprietary HP PIGLET (Personal Interactive Graphic Layout EdiTor).
 * DESI-III

Sculpting
https://www.nchsoftware.com/meshmagic3d/index.html

https://www.reddit.com/r/cad/comments/8dmtc8/please_share_your_experience_with_the_available/


 * http://ayam.sourceforge.net/ --- free 3D modelling environment for the RenderMan interface, distributed under the BSD licence

A number of these are listed above and should be moved.


 * Blender
 * EQUINOX-3D
 * DeleD CE
 * Structure Synth
 * Moonlight|3D
 * OpenFX
 * Fragmentarium

Free online tool which will export to STL: http://kovacsv.github.io/JSModeler/documentation/examples/bezier.html

Post-processing
Voronoi hollowing: http://www.voronator.com/

Gears
See also Section 6.2, Practical part geometries: Creating spur gears of the Guerrilla guide to CNC machining, mold making, and resin casting.

There is an Excel spreadsheet for clockwork calculations: http://www.shapeoko.com/forum/viewtopic.php?f=7&t=5190&p=38066

For information on wooden gears, see woodgears.ca, esp. the Gear template generator. See also Github: SVG generating interactive gear maker.

Extensive tutorial at: http://www.cartertools.com/involute.html

OpenSCAD http://www.thingiverse.com/thing:3575

Inkscape has an extension for gears: Effects | Render | Gear...

http://www.reddit.com/r/3Dprinting/comments/32v7t3/designing_gear_help/

http://cadquest.com/books/pdf/gears.pdf

Creating Involute Bevel Gears in Autodesk Inventor Using the Zweerink-Snider Process

Gear generator for Solidworks (Straight / Helix / Herringbone)

PCB
Discussion: https://www.reddit.com/r/cad/comments/5zxjln/what_do_you_guys_use_for_electrical/

See also Qucs (Quite Universal Circuit Simulator) and XCircuit and gplEDA (list of Electronic Design Automation (EDA) tools released under the GPL).

http://www.pcbweb.com/

http://expresspcb.com/ExpressPCBHtm/Free_cad_software.htm

http://opencircuitdesign.com/magic/

http://darwinne.github.io/FidoCadJ/download.html --- (Java) a free graphical editor for (more than) electronics

https://123d.circuits.io/

http://www.pcb123.com/pcb123.aspx

http://www.4pcb.com/free-pcb-layout-software/

http://www.diptrace.com/download.php

http://davbucci.chez-alice.fr/index.php?argument=elettronica/fidocadj/fidocadj.inc

https://www.tinycad.net/ --- http://sourceforge.net/apps/mediawiki/tinycad/index.php?title=TinyCAD

http://pcb.gpleda.org/

http://www.verilog.com/ --- https://github.com/FPGAwars/icestudio

Circuits

 * https://fritzing.org/home/
 * https://www.ctan.org/pkg/circuitikz
 * http://www.falstad.com/circuit/
 * https://github.com/rowhit/asy_circuit

Special Purpose
http://touch-mapper.org/ --- exports STL files from OpenStreetMap data.

http://www.makehuman.org/

http://www.derekhugger.com/tools/dsHypoGen.zip --- dsHypoGen is a Python script that calculates parameters for generating dual stage hypocycloid reducers.

http://valentina-project.org/ --- cross-platform patternmaking program which allows designers to create and model patterns of clothing.

http://commonwealthrobotics.com/#BowlerStudio ---robot development application that combines scripting and device management to allow the design of printable walking robots. 

Aircraft (incl. models)
UIUC Airfoil Coordinates Database--- Tool to generate OpenSCAD coordinates: http://chaaawa.com/airfoils/

https://github.com/booya-at/OpenGlider

https://opendesignengine.net/projects/yavin-thruster/wiki

Bicycles

 * http://rattlecad.sourceforge.net/ --- Opensource Bicycle framebuilding CAD app
 * https://www.bikecad.ca/java_1.8_security --- free browser version of commercial app
 * https://github.com/occamsshavingkit/Bike-Draw — a PostScript program for drawing bike plans.
 * A Catalogue of Spoke Patterns (github)
 * http://gear-calculator.com/

Boats

 * http://bearboat.net/index.html
 * http://carlsondesign.com/projects/hull-designer/
 * http://sourceforge.net/projects/freeship/
 * http://www.delftship.net/ --- free version can do various calculations and export to various formats.
 * https://seagrant.mit.edu/ESRDC_library/Epps-OpenProp-2009.pdf

Clocks
clockit: Free 3D Clock Designer

https://clocktickgenerator.makertoolmaker.com/

Parametric
http://www.mattkeeter.com/projects/kokopelli/

Mechanical modeling

 * https://gitlab.com/damien.andre/openmeca --- https://www.reddit.com/r/cad/comments/44kzi3/a_free_software_to_model_mechanical_systems/
 * http://blog.rectorsquid.com/linkage-mechanism-designer-and-simulator/

See also http://www.rs-online.com/designspark/electronics/eng/page/mechanical listed above and the CAM page which lists special-purpose programs for gears and fret and thread cutting.

Organic modeling
http://www.makehuman.org/ --- 123 Approach to 3D Modeling of Humans and Faces for CNC.pdf

Robotics
http://commonwealthrobotics.com/ Bowler Studio Alpha Release

Textures
Carbide Create has creating textures as a native feature.

http://paulrowntree.weebly.com/standingwave.html

Instructions
https://jig.space/create

Project Management
http://www.openplm.org/trac

Other design software
3D CG to 3D Printable 3D model converter for Windows PC --- CGto3DPrint is a free software that converts 3D CG(Computer Graphics) models to 3D printable manifold 3D models using MeshLab for surface mesh to voxel conversion and Blender for baking color textures. Converted 3D models are automatically exported from Blender to STL file for single color 3D Printing or manually exported to PLY file for full color 3D Printing. 

https://github.com/DEF7/TGA2STL --- Command-line utility for generating optimized STL meshes from TGA depthmaps. 

http://3dslice2d.com/ --- https://www.reddit.com/r/CNC/comments/8szvwi/3d_printing_using_2d_devices/

https://dynamobim.org/

See Online resources: SVG generators

Conversion
http://kabeja.sourceforge.net/ --- works well for DXF -> SVG.

https://convertio.co/

3D Scanning
Redrawing may be a better option: https://www.reddit.com/r/cad/comments/4mmqno/im_trying_to_reverse_engineer_a_component_to_draw/

FreeLSS --- laser scanning program for the Raspberry Pi. It allows a Raspberry Pi to function as the core to a complete turn table laser scanning system. Files for printing a 3D scanner: http://www.murobo.com/printables.html

http://ccwu.me/vsfm/ and http://www.danielgm.net/cc/ allow one to use a high quality camera rig to derive 3D shapes from photographs of objects.

Photo measuring app

 * Partometer --- http://www.vistechprojects.com/app/partometer
 * https://play.google.com/store/apps/details?id=com.vistechprojects.partometer
 * https://itunes.apple.com/us/app/partometer-camera-measure/id689675004?mt=8

3D Scanning Hardware
http://www.nextengine.com/

3D Probing
https://github.com/martin2250/OpenCNCPilot

Additional programs which may merit investigation
List to investigate: https://www.tech-edv.co.at/05_LUnIx/80_CAD~2f3d/10_CAD~20Links/index.php and https://help.ubuntu.com/community/UbuntuScience#Engineering%20Sciences


 * http://www.metaseq.net/ --- supposed to have a free licensing option
 * https://sourceforge.net/projects/mesh2hmap/
 * http://www.monolith.zone/features#introduction
 * https://www.openmodelica.org/
 * https://3dc.io/
 * https://www.matterhackers.com/store/l/mattercontrol/sk/MKZGTDW6 --- for 3D printing, but includes design functionality
 * https://sourceforge.net/projects/nurbana/
 * https://code.google.com/archive/p/monoworks/
 * http://www.misfitcode.com/misfitmodel3d/ https://sourceforge.net/projects/misfitmodel3d/
 * http://cv3d.com/
 * https://sourceforge.net/projects/nurbana/
 * http://www.crobics.com/en/index.php --- free online 3D modeling
 * http://www.artifice.com/free/dw_lite.html
 * https://www.leocad.org/
 * http://www.3dsystems.com/shop/support/invent/videos
 * https://www.plm.automation.siemens.com/en/products/solid-edge/free2d/
 * http://meshmixer.com/
 * magicavoxel http://ephtracy.github.io/index.html
 * https://www.3dslash.net/index.php
 * https://sourceforge.net/projects/misfitmodel3d/
 * http://www.seamless3d.com/ --- free opensource (MIT license) 3D modeling software
 * http://www.code-aster.org/
 * http://www.tflex.com/student/
 * http://www.doublecad.com/Products/DoubleCADXT/tabid/1100/Default.aspx
 * http://www.drawease.com/index-en.htm
 * http://www.cademia.de/en/?folder_id=258
 * http://www.tekhnelogos.com/powerdrawindexEn.html
 * https://opendesignengine.net/projects/mtk/wiki --- Mach 30's Mathematics Tool Kit, unified engineering analysis and documentation tool
 * http://www.johannes-raida.de/jnetcad.htm
 * http://dyama.github.io/siren/ --- simple CAD viewer for Microsoft Windows.
 * https://github.com/christopherpoole/cadmesh --- A CAD file interface for GEANT4
 * http://christopherpoole.github.io/A-CAD-interface-for-GEANT4/
 * http://sourceforge.net/projects/elmerfem/ --- Elmer finite element software Open source finite element software for multiphysical problems
 * http://sourceforge.net/projects/ocadis/
 * http://www.opencascade.org/
 * http://www.lemkesoft.de/en/products/cadintosh/ venerable Mac OS app from Germany, updated for OS X.
 * http://www.allycad.com/homeversion.asp --- UK
 * http://www.cadlogic.com/cad-software/draft-it/default.asp
 * http://www.cadvance.com/65form.htm ---Free CADVANCE 6.5 for Windows, re-release of CADVANCE Version 6.5, a CAD software system designed for Windows 3.1, originally released in 1995 now available to anyone free of charge.
 * http://www.graytechsoftware.com/products/cadx11/cadx11free.asp
 * http://milkshape3d.com/ --- low-polygon modeler initially designed for Half-Life.
 * https://clara.io/
 * http://www.caelinux.com/CMS/
 * http://www.routoutcnc.com/routout.html
 * gsculpt
 * http://www.justcad.com/index.html
 * http://home.centurytel.net/bwclark/
 * FreeDraft
 * GtkCAD --- (abandoned) modular, full featured, modern CAD/CAE/CAM system for GNU/Linux.
 * JCad --- 2D CAD application written completely in Java. AutoCAD DXF native format.
 * oCADis --- 2D CAD system for Linux. Basic drawing objects: line, arc, circle and more. Supports HPGL (export), DXF (import and export), PostScript output.
 * ThanCAD --- 2dimensional cad, with raster inclusion capability and emphasis in engineering. Written in Python using the wxPython library.
 * PythonCAD --- R38 https://sourceforge.net/projects/pythoncad/
 * AnyCAD 1.4 Free Version --- Chinese CAD program available in English
 * K3DSurf --- Program to visualize and manipulate Mathematical models in three, four, five and six dimensions. Supports Parametric equations and Isosurfaces.
 * Frusta --- Tcl toolkit to manipulate data for a 3d-printer
 * HYCAD 5.33 --- Free (abandoned? Last Updated: December 5th, 2007) CAD app for Windows from China by JiangJiang (developer homepage English link is 404, main site times out). Simplified AutoCAD interface, mouse gestures.
 * LiteCAD --- 2D CAD program.
 * A9 CAD
 * Replath --- a program that can plot various 2D file formats either directly to a RepRap or to a GCode file.
 * eCabinet --- CAD for custom cabinet makers (requires membership/registration)
 * gCAD3D --- 3D - CADCAM - software for MS-Windows and Linux (available in German and English) c.f., https://sourceforge.net/projects/gcad/
 * Misfit Model 3D --- an OpenGL-based 3D model editor. It supports multi-level undo, skeletal animations, texturing mapping, scripting, command-line batch processing, and a plugin system for adding new features.
 * CADemia-Community --- free Java CAD software for true-to-scale technical drawings and documents. Also available in German
 * Fandango: scripted 3d CAD --- formerly elcad, a python scripted 3d CAD application.
 * AR-CAD - freeCAD and StCAD --- not the FreeCAD above, free 3D CAD Software with Motion Simulation Capabilities.
 * AnyCAD --- .net Windows program / programming library
 * GNU CNC CAM --- Tool for converting DXF (CAD) Files to G-Code (RS-274) NC-Files.
 * CNCSimple ---3D modeling C# source code for Visual Studio Express 2010 at.
 * Minos3D --- Windows program to avoid wireframe views.
 * MonoWorks --- a full-featured, Open Source 3D Computer Aided Design (CAD) suite that includes object-oriented math and modeling libraries, as well as interactive viewing and modeling applications.
 * AutoQ3D --- Opensource (GPL) version is AutoQ3D Community available for Windows here. Mac, iPhone/iPad, Android, Windows and Linux versions are available for AutoQ3D CAD.
 * netfabb Studio Basic --- Free application for Linux, Mac OS X or Windows for mesh edit, repair and analysis
 * Wildcat CAD --- A modern 3D solid modeling kernel and associated applications for CAD and all types of related engineering. BSD license, last up-dated Oct 2008.
 * pyturn a simple python code generator for cnc lathe programs
 * 3DCrafter --- Real-time 3D modeling and animation tool that incorporates an intuitive drag-and-drop approach to 3D modeling. Free, Plus and Pro versions.

Bézier drawing programs
https://www.draw.io/

Opensource

 * https://gravit.io/ --- Chrome
 * http://ipe.otfried.org/
 * http://al.chemy.org/download/ (opensource, cross-platform)
 * https://inkscape.org/ --- listed above
 * http://www.skencil.org/
 * https://krita.org/ --- also has painting / pixel image features
 * https://www.calligra.org/karbon/ --- also see flow, a diagramming tool.
 * http://www.vpaint.org/ --- cross-platform, supports: Linux, Mac OS X, Windows

METAPOST is a special case in point, see http://cseweb.ucsd.edu/~s1pan/MEPer/

Mac OS X

 * http://www.cenon.info/frame_gb.html --- listed above, CAM module is a commercial option
 * http://al.chemy.org/download/

SVG

 * http://www.drawsvg.org
 * http://vectorpaint.yaks.co.nz
 * http://editor.method.ac
 * https://boxy-svg.com
 * https://glyphter.com
 * https://ravichugh.github.io/sketch-n-sketch/ --- notable for allowing manipulation of the output to be reflected in the code.

Free

 * http://www.nchsoftware.com/drawpad/index.html (Windows)
 * http://www.serif.com/free-graphic-design-software/ (Windows)
 * https://vectr.com/downloads/ --- beta (Mac, Windows, Linux, Chromebook)
 * Vector Paint http://yaks.co.nz/
 * https://hundredrabbits.itch.io/dotgrid

Tutorials
https://www.reddit.com/r/3Dprinting/comments/bm6wq2/so_you_want_to_learn_x_program/

Moribund

 * http://freeengineer.org/FREEdraft-dead.html
 * http://avocado-cad.sourceforge.net/
 * https://github.com/mmik005/js-cad https://sourceforge.net/projects/js-cad/
 * Shapesmith --- 3D modeling (Opensource) Parametric, Open-Source 3D Modeling in your browser, can do basic primitives and addition/subtraction operations and export to STL. https://github.com/bjnortier/shapesmith Deprecated: https://twitter.com/shapesmith/status/704719005857280000