Google( Trimble) SketchUp 3D Modeling Software

http://sketchup.google.com/

• SketchUp is fast, fun and intuitive
• Visualize anything in 3D
• Share models with colleagues and friends

STL Plug-in su2stl

http://rhin.crai.archi.fr/rld/plugin_details.php?id=429

Exports/imports selection or whole model to/from STL format external file, units support.

Download and drag into "plugins" folder. 

• Readme for su2stl
• skp to dxf export ( for lasercutting)
• SketchUp to Dxf or STL (most versatile)

STL (STereoLithography) is a file format native to the stereolithography CAD software created by 3D Systems. STL is also known as Standard Tessellation Language^[1] This file format is supported by many other software packages; it is widely used for rapid prototyping and computer-aided manufacturing. STL files describe only the surface geometry of a three dimensional object without any representation of color, texture or other common CAD model attributes. The STL format specifies both ASCII and binary representations. Binary files are more common, since they are more compact ^[2].

An STL file describes a raw unstructured triangulated surface by the unit normal and vertices (ordered by the right-hand rule) of the triangles using a three-dimensional Cartesian coordinate system.- Wikipedia

Tutorials:

• Getting Started in Google SketchUp (Video-Building a House)
• Getting Started in Google Sketchup Part 2
• Getting Started in Google SketchUp, Part 3Designing Interiors, Offset Tool, Components, matching dimensions

Daniel Tal SketchUp Site Design Tutorials