Your design must be a three-dimensional solid object to output an .STL file.

AutoCAD (Versions: R14-2000i)

• Be sure the model is in positive space
• At the command prompt type "FACETRES"
• Set FACETRES BETWEEN 1 &10. (1 Being low resolution and 10 high resolution for .STL Triangles)
• Next, at the command prompt type "STLOUT"
• Select Objects
• Choose "Y" for Binary
• Choose Filename

IronCAD

• Right Click on the part
• Part Properties > Rendering
• Set chord height to .001
• File > Export
• Choose .STL

ProE

• File > Export > Model (or File > Save a Copy)
• Set type to .STL
• Set chord height to 0. The field will be replaced by minimum acceptable value.
• Set Angle Control to 1
• Choose File Name
• OK

ProE Wildfire

• File > Save a Copy > Model
• Change type to .STL (*.stl)
• Set Chord Height to 0. The field will be replaced by minimum acceptable value.
• Set Angle Control to 1
• OK

SolidEdge

• File > Save As
• Set Save As Type to .STL
• Options
• Set Conversion Tolerance to 0.001in or 0.0254mm
• Set Surface Plane Angle to 45.00
• Save

SolidWorks

• File > Save As
• Set Save As Type to .STL
• Options > Resolution > Fine > OK
• Save

Unigraphics

• File > Export > Rapid Prototyping
• Set Output type to Binary
• Set Triangle Tolerance to 0.0025
• Set Adjacency Tolerance to 0.12
• Set Auto Normal Gen to On
• Set Normal Display to Off
• Set Triangle Display to On