DraftSight 3D: How to

This is more of a quick reference guide than a tutorial.  If you follow the instructions given here, you'll be able to experiment with 3D in DraftSight and discover new stuff.  When you discover something that might be useful here, please send me a comment.  I won't post it as a comment, but if it's useful I will add it to the main text of this article - I'll add your name or ID at the bottom of the article.

What can you do with a DraftSight 3D CAD model?
Unfortunately, right now you can't do much besides play with it inside DraftSight.  Somebody please enlighten me.
When you save it as a DWG file, it saves all the 3D data.  You can confirm that by exiting and restarting DraftSight, and then reloading the DWG file.
But the 3D doesn't import into Creo Elements/Direct Modeling Express.
I don't know about MilkShape or UVMapper yet.
The free version of DraftSight doesn't let you export the file in a different format.
???

What is the CCR?
You'll see the initials "CCR" in a lot of the DraftSight documentation.  CCR stands for Cartesian coordinate reference.  It's the little X-Y widget in the lower left corner of the Model view when you first start up DraftSight.  There's actually a Z axis on it as well as the X and Y axes, but you won't see it until you start "rolling the view."  The CCR will help you maintain your orientation when you're viewing objects in 3D.

How to view in 3D
Viewing things in 3D is easy.  You can even view a 2D drawing in 3D!  That's kind of funky and not really useful, but it's fun to do once or twice.
1. From the main menu, select View --> Constrained Orbit.
  - OR -
  From the command line, type ROLLVIEW and press Enter.
  The mouse cursor changes to a circle thingy.
2. Hover the mouse over an object in your drawing.  Hold down the left mouse button.  The mouse cursor changes to two 3D circle thingies.
3. With the left mouse button still down, move the mouse.  You'll get the hang of it.
4. To return the mouse function to normal, press Esc, press Enter, or right-click the mouse.  This doesn't return the 3D view to normal.

How to return the 3D view to normal
Here's the really quick way:  At the command line, type -V O T. That's short for -Views, Orthographic, Top.  The dash is important:  without the dash, you get the dialog box.

(UPDATE, 9 Feb 2012: Here's an even quicker way, pointed out by an alert reader: type PLAN and press Enter. It worked in AutoCAD, and it works in DS too.)

Here's the conventional way:
1. Either type V (short for VIEWS) and press Enter, or select View --> Named Views from the main menu.
2. In the dialog box, select View Type --> Defaults.  Select Top view, and click OK.

By "normal" I mean:
- You get a 2D view, showing the XY plane.  The CCR shows X and Y axes only.
- A Zoom Fit is automatically executed, so everything shows in the drawing area.
- This doesn't put the CCR at (0,0,0), but it does put it in the lower left corner of the drawing area.

How to create wireframe shapes
1. From the command line, type 3D and press Enter.
2. You can select from 9 different shapes:
Box - specify Length (+X or RIGHT), Width(+Y or UP), Height (+Z or into screen), and rotation about Z-axis (this is rotation in the 2D plane, with 0 being +X and numbers increasing towards +Y.  You can also make a cube and a square box using the C shortcut after Length or Width.
Cone
Dish
Dome
Mesh - specify four corners of a rubber sheet, and how many segments you want between the corners.  M and N are difficult concepts to explain, but they'll make sense when you see them.
Pyramid
Sphere
Torus
Wedge

How to extrude 3D shapes from a 2D cross section
1. Create the 2D shape.  It doesn't have to be on the Z=0 plane, but it all has to have the same Z value (that is, parallel to the Z=0 plane.
2. From the command line, type EXTRUDE and press Enter.
3. Click the 2D shape.
4. Either enter a numeric number (positive or negative) for the extrusion height in the Z direction,
  - OR -
  If you are viewing the shape obliquely (from ROLLVIEW or something), you can just move the mouse to the extrusion height you want, and left-click to set it.

How to rotate and stretch 3D shapes in 3 dimensions
???

How to create primitives
These are all in the Draw-->Mesh submenu.
2D Solid - Also the SOLID command.
This creates a shape with faces, not just a wireframe.
If you're using the mouse, you specify 3 corners of a triangle, or 4 corners of a quadrilateral - but if your specifying a quadrilateral, don't go in a circular motion.  You have to go in a zigzag.  If you go in a circular motion, you get the dreaded butterfly effect.  After you specify 3 corners and press enter, it draws a triangle.  After you specify 4 corners, it draws a quad.  The last 2 points now become the 1st and 2nd points of the next side, and you can specify new 3rd and 4th points.  In this way, you can create a long polygon of quads all stitched together.
3D Face - Also the FACE command.
I'm not clear on the difference between this and 2D Solid.  They both seem to do the same thing for me.
3D Mesh - also the MESH command. 
I explained this earlier.
Revolved - also the REVOLVEDMESH command.< This creates a solid of rotation.  Draw a 2D shape you want to use as your revolved surface, and draw a straight line (or pick a straight feature, like the edge of a box) to use as the axis of rotation.  The elements don't have to be on the Z=0 plane, or any other plane; nor do they have to be coplanar.  Unfortunately, I don't know the Setup option to give you more than 6 segments in the rotated solid.<
Tabulated - also the TABULATEDMESH command.
This is like EXTRUDE, only its direction and distance of extrusion is not dependent on the Z axis. 
1. Create a 2D shape on a horizontal (Z = constant) plane. 
2. Draw a line the direction (3D) and distance you want to go. 
3. Execute the command from the menu or the command line.
4. "entity for path curve" is the 2D shape you want to extrude.
5. "Entity for direction vector" is the line defining distance and direction.
Edge - also the EDGEMESH command.
This command takes four "open" entities (line, arc, polyline, spline, etc.) and draws a rubber-sheet mesh between them all.  Their ends have to be touching, to make 4 vertices.
Ruled - also the RULEDMESH command.
This command takes two entities and joins them to make a solid with the two entities as faces.
1. If one entity is a point and the other a closed element (rectangle, circle, polygon) then you end up with a cone or a prism.
2. If one entity is a point and the other an open element (line, spline, curve), you end up with a fan.
3. If both are open elements, you end up with the rubber sheet mesh.
4. If both are closed elements, you end up with a cool 3D adapter thingy like the vent hood above the grill at a Mongolian Barbecue restaurant.

How to create 2D shapes with some thickness to them, and on a different plane
The ZPLANE command lets you add thickness to your 2D objects.  It also lets you draw on a different Z plane than the default Z=0 plane.
1. From the command line, type ZPLANE and press Enter.
2. Type the value for the new Z plane, then press Enter.
3. Type the thickness for the objects you're about to draw, then press Enter.

How to join primitives to make 3D objects
???

How to join 3D shapes and objects to make more complicated objects
???

How to color faces, and how to hide unseen surfaces
The Hatch/Fill function can be used to select and color faces.  I suggest just using the "fill" capability.  Unfortunately, selecting the face to color doesn't work reliably for me.  I guess I haven't discovered the trick yet.
1.  Click on the Hatch/Fill icon in the menu on the left side of the drawing area
- OR -
Select Draw --> Hatch/Fill from the main menu
- OR -
On the command line, type HATCH and press Enter.
2. In the dialog box that comes up:  in the Type box, select Fill.  In the Colors box, select a color.  You can also change the Style and Orientation.  Don't hit OK yet - it's probably greyed out anyway.
3. In the Boundary settings box, click Specify Points.  The Hatch dialog temporarily disappears, so you can choose a face to color.  Click on any area inside the face, then press Esc or Enter. (WARNING:  THIS DOESN'T ALWAYS WORK!)
3a. While the Hatch dialog is temporarily absent, you can also turn or manipulate the 3D object to find the face you want to color, by selecting View-->Constrained Orbit from the main menu.  When you have finished manipulating the 3D object, press Enter or Esc to return to the view that lets you select a face.
4. After you have selected a face and returned to the Hatch dialog, click OK.

If you know of a more reliable way to select the face to color, please comment on this article. I won't post your comment, but I will edit the article and put your name or ID in the acknowledgements.

How to change the lighting so the 3D item is easier to see
???

Acknowledgements
Thanks to these people who have helped to expand my knowledge of DraftSight's 3D capability, and to make this guide more complete:
Anonymous, for telling me about PLAN.