Another option is to use a Spline (Method = CV, Degree = 2). This will produce a mathematically/geometrically perfect parabola curve that will allow accurate Perp and Tan OSNAPs. Examine the attached example to understand construction...
This probably does not qualify as a proof but:
If you analyze an Isometric direction it will show 1, -1, 1 (for SouthEast Iso). So, rotating the 2D geometry by that amount about the hinge bc by 45 degrees makes sense because ACOS(1/SQRT(2)) = 45.
For the next step, though, the angle off of...
I believe you will need the new 3D Modeling tools of 2007. Sadly, I do not have access to that version, so I'm no help on the command sequence.
The critical thing for this same procedure in Rhino was generating the "compound" loop to serve as a path. Once that is in hand, however, any profile...
This is what I picture from the OP description.
http://www.box.net/shared/0u177vpco8
If it is indeed the model required, it is not easily accomplished in Autocad; certainly not with anything older than 2007.
This was imported to 2004 (the version to which I have access) from Rhino V4.
Certain filtering values can be stacked to allow for more compact code, plus additional functionality is available with the Wildcard operator "*".
intCode(0) = -4: varCodeValue(0) = "<AND"
intCode(1) = 0: varCodeValue(1) = "LINE,LWPOLYLINE,POLYLINE"
intCode(2) = 8...
