Rhino published a great tutorial for 3d printing with Rhino 5. Here are the highlights and link to the full pdf.
General Principles •
Only closed surfaces, closed polysurfaces and closed meshes will export correctly to an .stl file.
Document Set Up •
There are 3 main areas to focus on:
- units and tolerances will allow better control during the design process and easy export to .stl - Model units – Millimetres Absolute tolerance – 0.01
- display options can be set in a way that will allow you to spot any potential problems during design process - “colour backfaces” and “flat shading”
- additional toolbars can be loaded to allow access to .stl specific commands - Analyze and STL Tools will allow quick access to .stl specific commands
Basic Drawing Rules •
CheckNewObjects option at the very beginning of the design process
Osnap is very helpful in correct modelling
Avoid trimming polysurfaces, and use boolean operations instead. A good alternative to trimming is the WireCut command
Try to avoid Patch command
Depending on the geometry it is advisable to use extensively different construction planes CPlane
How to Find and Fix Problems •
The first step is to check the object in Properties panel. Closed surfaces, closed polysurfaces and closed meshes will be exported correctly to .stl file.
Alternatively SelBadObjects command selects all the bad objects at one go.
The PDF has great information on fixing your model if it has bad objects.
Correct Settings for .stl Export •
Mesh polysurfaces and surfaces at the suitable resolution. Additional instructions are in the PDF.
With your objects selected type Export or go to menu > file > Export selected and choose destination folder and a name for the file.