3D printers can produce objects through computer-aided design or 3D scanning, and some high-quality 3D design applications are available for free. Here is a round up of the different 3D modelling software that you can download at no cost.

Google SketchUp
Google SketchUp is an accessible 3D modelling program that still retains some of the power of its 'Pro' version. Google SketchUp's free version allows you to export 3D models to DAE and KMZ file format, but also allows you to save elevations or renderings of your 3D model, commonly known as 'screenshots', in BMP, JPG and TIF file formats.

SketchUp also includes integrated tools for uploading content to Google Earth and Google's 3D Warehouse. From within the program you can adjust your perspective to see your drawing from different angles and can also label your models.

3DTin
3DTin is a browser-based 3D modelling application that requires no installation, but requires that any 3D sketch you create be shared under Creative Commons. With 3DTin, you can export your 3D drawing in STL, OBJ and DAE file formats. 3DTin has a library of templates and an intuitive interface, as well as tutorials. Sketches are stored in the cloud, so you can access and share them with anyone using a unique URL. For private storage, you must sign up and pay for premium membership.

Blender
Blender is a freely available open-source 3D modelling application. Blender is typically used to create animated films, visual effects, art, 3D printed models, interactive 3D applications and video games. When it comes to 3D prints, Blender's features include modelling, texturing, sculpting, rendering and compositing. Blender uses its own file format, BLEND, but this type of file can be converted to other file formats with the right software. Blender's interface works best for fast workflow.

OpenSCAD
OpenSCAD is an OpenGL 3D modeller application that allows you to create solid 3D CAD objects. Rather than being an interactive modeller, OpenSCAD is a 3D compiler. The application reads data from a script and then renders the model based on this script. OpenSCAD uses a technique called Constructive Solid Geometry, creating a complex surface or object by using Boolean operators to combine objects. OpenSCAD can also extrude forms from AutoCAD DXF files. For the most part, the results of the computational geometry algorithms are rendered into 3D STL files.

Tinkercad
Tinkercad is a solid modelling, web-browser application. Tinkercad uses WebGL for storing your drawings. Specifically tailored for laser cutters, Tinkercad provides for exporting SVG files as well as extensive 2D and 3D import capabilities. Tinkercad will integrate directly with your 3D printer, supporting all printers on the market as well as the standard STL file format. Tinkercad also provides a large range of tutorials to get you started with the application.

With the options available for free 3D printing software, you don't have to look far to get started on your way to printing 3D objects. While these options are free, most of them offer premium, paid versions of their software with greater capabilities for more serious work. 

Steve Erickson, vice-president for sales and engineering, brings more than 30 years of experience in the plastic injection molding design industry to First American Plastic Molding Enterprise and Quad, both in South Beloit, USA. First American Plastic Molding Enterprise is a custom plastic injection-molding manufacturer that specialises in 3D printing.