Hi Paul - in general you can't grab individual faces and edges, because often times those edges are not actually edges of the "underlying surface" and are instead "trim edges" which are marking areas of a surface as being holes or cut away parts.

A box that you create with Draw solid > Box is a special case though - you can turn on control points for a box with Edit > Show pts and then select 2 points for one edge, or 4 points that make up one face and then scale or move those points around.

But like I said, that's a special case - after you have done some boolean operations your objects will be made up of surfaces that have trim curves on them instead of all untrimmed surfaces like the box happens to be.

So in general in MoI you don't pull edges or faces around like you would do in a polygon modeling type program - instead the regular way to make something like a pyramid shape would be more to draw it directly by drawing 2 rectangles one above the other, scale the upper rectangle down, and then construct the pyramid by doing a loft between the 2 rectangles.

That's more of the general workflow - draw profile curves, which you can shape however you need (by control point manipulation, scaling, offsetting, whatever), and then construct the final shape that you want from those curves, rather than starting with some other shape like a box and modifying it - that's more how a polygon modeling program works which has a much different workflow.

There is some more information on how an "underlying surface" works in the FAQ answer here:
http://moi3d.com/wiki/FAQ#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F
That tries to explain how objects with trim curves are structured, and why it doesn't really work to try and edit one surface when you've got 2 of them that are meeting up at trim edges.

Also see here for some other various posts with additional explanations on this subject:

http://moi3d.com/forum/index.php?webtag=MOI&msg=4605.7
http://moi3d.com/forum/index.php?webtag=MOI&msg=3628.200
http://moi3d.com/forum/index.php?webtag=MOI&msg=4052.6
http://moi3d.com/forum/index.php?webtag=MOI&msg=4050.3
http://moi3d.com/forum/index.php?webtag=MOI&msg=4360.9
http://moi3d.com/forum/index.php?webtag=MOI&msg=3539.1

 

Basically the way MoI's modeling paradigm works is more like "construct objects from drawn curves" and not so much like "tweak edges and faces of a 3D solid" like a polygon modeling program.

But it's also because of this different style approach that MoI has a totally different set of strengths and weaknesses as compared to a polygon modeling program which is really what makes it a nice companion, because the "construct from curves" approach tends to work really nicely with a wide variety of mechanical or man-made type objects that are defined well by 2D profile curves.


Hope this helps to explain things a bit more!

- Michael