Autodesk's Tinkercad is a free Web-based design tool that enables you to create 3D objects, then download those creations in a printer-friendly format. Here's how to get started.

For €500 ($598) or less, space geeks, or just about anyone, with a 3D printer can build their own ExoMy, the younger and smaller sibling of the real Mars rover, thanks to the Laboratory.