Start with a Good .STL or .OBJ
Exporting Your Model as .STL or .OBJ
The PreForm software can import models saved in the .STL format, the most common file type for 3D printing. Most 3D CAD packages can export directly to .STL or have add-on tools to help. PreForm also accepts the .OBJ format exported by most animation software. The larger the .STL or .OBJ file, the longer PreForm will take to import it.
Consider reducing the file size when exporting from your 3D CAD package. There is not a definitive upper limit on the size of a file you can open in PreForm, as it is dependent on your hardware. PreForm will handle models with about 3 million vertices on most hardware. Higher-end hardware will be able to open bigger models. Most CAD programs should say how many vertices are in a model when you export a file .
Meshlab is a free software tool that can convert several 3D CAD file formats to .STL or .OBJ.
All 3D CAD is great for creating printable models, but some 3D CAD tools export better than others. PreForm will attempt to repair any mesh defects in your models to make them ready for printing. PreForm utilizes NetFabb's automatic model repair functions to repair your 3D model upon import, making it easy for you to print without worrying about model integrity.
Units (and Scaling) in PreForm
PreForm always assumes that the values in an .STL or .OBJ file are in millimeters.
If you intend your model's units to be inches, select the model and select the “in” option under Model Units in the Edit menu. This will make the model appear 25.4 times bigger. This is because a “1.0” in the .STL file now means 1.0 inch instead of 1.0 mm.
On the other hand, if you saved the model in units of meters, a cube with 3cm (0.03m) edges will be read by PreForm as having 0.03mm side lengths. 30 microns is ten times smaller than the Form 1+'s minimum feature size, and PreForm will automatically scale such a model by a factor of ten or more, so that it's large enough to print.
If an imported model is bigger than the build volume, PreForm will scale down the model to fit in the build volume when it is opened. If you open the scale tool, you'll see how much the model was scaled.