Lately there has been a focus on 3D, and I am not referring to 3D television sets. I'm talking about 3D printing. Today I want to take a step back and bring to your attention what comes before 3D printing. The answer of course is 3D designing. There are many high-end programs to help you design and model in 3D space, several are AutoCad, Maya, 3D StudioMax, Lightwave and Rhino 3D among others. These are all wonderfully robust feature packed pieces of software, however, these are aimed primarily at professionals in the industry. Any of these programs would be a fairly significant investment for a hobbyist, maker or someone just interested in testing the waters.
I want to focus on two main providers of free 3D software. They have similarities and differences and hopefully one of them will fit your needs. Both providers offer free software to get you designing in no time.
Blender - It has been a player in the 3D design world for a handful of years. The product is robust in its features offering: a customizable interface, character modeling, character rigging, solids modeling, animation, rendering, UV Unwrapping, Raytrace Rendering, physics and particles, shading, realtime 3D/game creation, imaging and compositing, camera and motion tracking, extensible add-ons and accepts a wide variety of file formats. It also works on all platforms: Windows, Mac and Linux.
Autodesk 123D - Although Autodesk is more widely known for their high-end programs, they have recently provided some free alternatives to help build the 3D printing industry. Autodesk has a group of 5 different apps in their 123D brand. They are 123D Catch (Automatically convert ordinary photos into extraordinary 3D models.), 123D Creature (Create 3D creatures and 3D print them right from your iPad.), 123D Design (Design the thing you want to make, and send it straight to a 3D printer.), 123D Make (Transform 3D models into a pattern for assembling real artful creations.) and 123D Sculpt (Shape and paint digital clay into amazing 3D sculptures.). 123D Design is obviously geared exactly for creating 3D printouts.