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.[1]

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 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.

The Failed Promise of Parametric CAD, a series of articles by Evan Yares[3]:

## 2D

2D drawing (Opensource) Inkscape SVG drawing program which can either export to DXF or directly to G-code using plug-ins. Supports pressure-sensitive graphics tablets.

Includes menu option to export to MakerCAM SVG.

2D CAD (Opensource) Simple2D CAD/CAM Windows app to cut simple shapes (pockets, mostly) and simplified gears, includes a geometry mode that allows geometry defined by lines and arcs. It also generates geometry from any OpenType font.
2D drawing (Opensource) Cenon (Mac OS X, NeXT/OPENstep, Linux) OpenStep CAD/CAM program which has transitioned to opensource.
2D drawing (Opensource) Xfig G-code enabled Xfig.
2D CAD (Freeware) Siemens Free 2D Free CAD software by Siemens (Windows). textbook available as a PDF.

Note that Draftsight is no longer freely available.

### 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/ [6]

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

## Extrusion

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

## Fonts

In many instances a single-line font is a desirable option for CNC. The Hershey Fonts in Inkscape are one notable option.

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

## 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.

3D modeling (Opensource) K-3D K-3D is free-as-in-freedom 3D modeling and animation software. It combines flexible plugins with a visualization pipeline architecture, making K-3D a versatile and powerful tool for artists. Available for Windows, Mac OS X and Linux.
3D modeling (Opensource) BRL-CAD BRL-CAD is a cross-platform open source solid modeling system that includes interactive geometry editing, high-performance ray-tracing for rendering and geometric analysis, image and signal-processing tools, a system performance analysis benchmark suite, libraries for robust geometric representation, with more than 20 years of active development. Discussion of shortcomings.
3D modeling (Opensource) Art of Illusion Free, open source 3D modeling and rendering studio. Features include subdivision surface based modeling tools, skeleton based animation, and a graphical language for designing procedural textures and materials. Default design software for the RepRap project.
3D modeling (Opensource) MeshLab Open source, portable, and extensible system for the processing and editing of unstructured 3D triangular meshes.

Converts Obj to stl?

A variety of macros are available, i.e., http://www.freecadweb.org/wiki/index.php?title=Macro_FCGear [9]

Print creation and assembly handling FreeCAD leave a lot to be desired.[10]

3D parametric modeling (Opensource) ImplicitCAD Similar to OpenSCAD (above), but written in Haskell and using an internal geometric representation, as opposed to the polygon mesh used by the former
3D modeling (Opensource) Blender Free, OpenSource and crossplatform 3D program. Allows modelisation, shading, rendering, animation, interactive 3D, compositing. Not a CAD software though it can be used for any kind of modeling. See Blender CAM for a tool to export files for EMC. If importing from Illustrator, see this forum discussion for a note on how to handle units.

Parametric interface inspired by Grasshopper: http://nikitron.cc.ua/sverchok_en.html https://github.com/nortikin/sverchok/ [14] See the new interface/fork at: https://www.bforartists.de/

3D modeling (opensource) Dilay https://github.com/abau/dilay --- https://www.reddit.com/r/programming/comments/46130v/dilay_a_free_3d_sculpting_application/
3D modeling (Opensource) Wings3D Free, OpenSource and crossplatform 3D modeler. Wings 3D is an advanced subdivision modeler that is both powerful and easy to use.
3D modeling (Opensource) SolveSpace Parametric 3D CAD program for Windows, Linux, and Mac OS X. See also its 2D predecessor, SketchFlat.

Originally a Windows 1.4Mb executable that didn't have to be installed.

Available on the web at: https://files.whitequark.org/SolveSpace/solvespace.html or see: http://notecad.xyz/ [15] also see: https://github.com/ppd1990/solvespace-snap and https://snapcraft.io/solvespace [16] or for Mac OS X at: https://github.com/whitequark/solvespace/releases [17]

Does basic 3D operations as well as 2D. A good free option for basic modelling, as well as for education (the basics are the same as any full featured parametric CAD system). Outputs in .svg. .stl output, should be pretty well suited to simple modeling for 3DP.[18]

Features include: Constraints and assemblies

Articles:

Forum discussions:

Videos[19]:

3D modeling (Opensource) POVray "The Persistence of Vision Raytracer (POVray) is a high-quality, Free Software tool for creating stunning three-dimensional graphics".
2D drafting/3D modeling (Opensource) lignumCAD Tool for designing furniture.
2D drafting/3D modeling (Opensource) Salome (or Salomé) Generic platform for Pre- and Post-Processing for numerical simulation. Can be used as standalone application for generation of CAD model, its preparation for numerical calculations and post-processing of the calculation results.
3D modeling (Freeware) Caligari Truespace Commercial program released to freeware. http://lunadude.com/rsrc_trueSpace.htm
3D modeling (Freeware) DesignSpark Mechanical Freeware software for Windows distributed by RS Components International.[21] Free version of SpaceClaim 2012.[22]
3D modeling (Freeware) FormZ Free Freeware software for Windows 7/8/8.1 and Mac OS X 10.7 or later.[23]
3D modeling (Freeware/Windows) Microsoft: 3D Builder Create, print (List of supported printers) and scan (requires Kinect v2 sensor) functionality.[24]
3D modeling (Freeware/Windows) Pixologic::Sculptris Sculptris is a free 3D modeling program by Pixologic (The makers of ZBrush), that many find to be a good starting point for learning 3D modeling.

It is also well liked for its efficient use of computer resources, and works well with laptops, or older operating systems, such as Windows XP SP2, for example. [25]

3D modeling (Chrome app) Design Something Google App Store 3D modeling application running on Chrome and Firefox. Pre-defined shapes, operations include extrude and sweep.
2D drawing (Opensource) Doodle3D Freehand sketching program for iPad and Mac OS X (source available for other platforms) to extrude and revolve into 3D.
• 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.[26]

Anim8or --- Windows 3D modelling tool able to import and modify .3DS files [27]

https://www.bricsys.com/en-intl/shape/ --- used in architecture.[28]

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

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/ [29]

#### Previewers

iPad STL viewer: 3D Push Source on Github [31]

#### Online modelers

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

http://edges.io/ --- noted as working well w/ a stylus.[32]

#### Image Depth Maps

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#Free

#### Bricks

http://prisma3d.net/ --- Android [35]

• HyperFun
• PLaSM

#### Sculpting

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/ [36][37]

## Gears

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

Gears Involute Spur Gear Builder Browser based utility for calculating and drawing involute spur gears, fully accounts for undercuts. Blog announcement.[40]
Gears GGGears [42] Tool for creation and calculation of gear transmission finite element models. Consists of a geometry and mesh generator based on GMSH and a finite element model based on GETFEM++.
Gears pyGear Built on top of pythonOCC, OpenCascade, numpy and scipy, serves as an CAE/CAD-preprocessor generator of involute gears.
Sprockets Sprocketeer (online) Windows and information Generate gcode or a CAD (DXF) drawing for sprockets.
Gears GearGCoderV1.0 (Windows) Generate gcode for a gear based on inputting Diameter (150mm --- values in parentheses are samples suggested by the developer), teeth (20), width ratio (3), feed rate (1000), tooth height (13mm), depth (9mm), add mounting holes (Y), number of holes (5), distance from center (50mm).[43]
Gears GearMaker (Windows) Program that will produce the tooth profile of a gear as a dxf drawing. Video tutorial on finishing.
Gears GearDXF (Windows) Outputs a DXF file containing a 2D outline of a spur gear using specified parameters. The tooth face is a true involute curve, but the base gaps between teeth are rough.[44]
Gears gears (Java) Involute gear milling generator and G-code viewer[45]
Gears Gear Model For 3D Printer (OpenJSCad website) Online gear generator includes support for rack and pinion, bevel and worm gears.

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

Inkscape has an extension for gears: Effects | Render | Gear...[46]

## PCB

PCB (opensource) KiCad Electronic design automation (EDA) software suite for designing schematics of electronic circuits and printed circuit boards (PCB).
PCB (opensource) gEDA Full GPL'd suite and toolkit of Electronic Design Automation tools.
PCB (opensource) QS Cad Tcl/Tk EDA Package. Schematic capture through to PCB layout. Has Part editor as well as editor for Schematic and PCB Decals.
PCB (opensource) Stripboard Designer 1.0 Open source (BSD) app written in freeware Visual Basic 2008 Express for Wintel machines. See also Stripes, a GPL Java version.
PCB (opensource) DIY Layout Creator (DIYLC) GPL Java software for creating stripboard and universal board designs.

## Special Purpose

3D modeling --- Surfboards BoardCAD Opensource CAD/CAM-system (written in Java) for surfboards.
3D modeling --- furniture SketchChair Opensource CAD/CAM-system for flat-pack furniture. Forums/troubleshooting
2D CAM --- Jigsaw puzzle piece cutter (Online - Silverlight) CNC Puzzle Maker Program for cutting out puzzle shapes w/ tabs.
2D CNC --- sails Sailcut CAD Sail design and plotting software.
2D CNC --- Parametric boxes Planter Box Generator[49] Javascript to generate jointed boxes for planters (and other uses).

http://touch-mapper.org/ --- exports STL files from OpenStreetMap data.[50]

http://www.derekhugger.com/tools/dsHypoGen.zip --- dsHypoGen is a Python script that calculates parameters for generating dual stage hypocycloid reducers.[51]

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. [52]

### Aircraft (incl. models)

3D CNC --- foam cutting for model airplanes Jedicut CNC Program for cutting out wings and fuselages.
3D aircraft modeling OpenVSP Vehicle sketch pad. NASA opensource parametric geometry. Described as suited for general use.[53]

UIUC Airfoil Coordinates Database--- Tool to generate OpenSCAD coordinates: http://chaaawa.com/airfoils/

### Mechanical modeling

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.

### Robotics

http://commonwealthrobotics.com/ Bowler Studio Alpha Release [65]

### Textures

Carbide Create has creating textures as a native feature.

## 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. [67]

https://github.com/DEF7/TGA2STL --- Command-line utility for generating optimized STL meshes from TGA depthmaps. [68]

### Conversion

http://kabeja.sourceforge.net/ --- works well for DXF -> SVG.[69]

## 3D Scanning

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.[71][72] 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.[73]

## Bézier drawing programs

### Opensource

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