Google SketchUp is a free 3D modeling software. Using the steps outlined by Eric William you will easily be able to convert your SketchUp design to something that can be 3D printed. Eric used a Solidoodle printer but this will work on any 3D printer. First step is to export from SketchUp in an STL file format. The STL file is imported into NetFabb where it is repaired if needed. You can now print this direct to your 3D printer or send it out to be printed.