Steel Stubs is an add-on programme for AutoCAD 2000 & Mechanical Desktop. It facilitates the development of 3D structural and mechanical models.
The data supports US, British and Australian standards and consists of hot rolled sections, cold formed zee/cee sections, square/rectangular/circular tubing, plate, flat bar, merchant bar (square/round), bolts (metric/imperial), grating and handrail. The sections are drawn parametrically from point/to point etc. You also have a facility to quickly add your own sections (enclosed/hollow) to a custom database by picking a 2D shape off the screen (very useful).
The tools to manipulate this data consist of drilling, cutting, coping, clash checking etc.
Also included is an excellent PowerPoint tutorial which will quickly have you producing models and extracting the necessary 2D drawings from it.