CAD Applications

Each CAD application handles geometry slightly differently. Some create objects as closed solids with an inside and an outside, while others like Google SketchUp just create planar 'faces,' which can be joined to create closed objects. Knowing the nature of the geometry created by the CAD application you are using will help determine what steps you need to take to make your model 3D printable.

The ultimate goal is to create a closed volume that describes the object you wish to print; be it a house, commercial building, cell phone case or anything else. Every program has a different way to achieve this goal. Some programs' snapping functions can ensure that two objects are joined well. Other programs' snapping is not as reliable, and objects must overlap. Some programs' geometry must be resurfaced to create a single solid, while a simple union boolean operation will create printable geometry from other programs.

The key is knowing the nature of the geometry created by the program being used, and how that geometry translates into a single, solid, 3D printable object.