Hi folks,
This is what I have so far with regard to “flattening” a cylindrical surface. The multitude of illustrations and the detailed step-by-step are for the sake of any newcomers to MoI. I create a form according to the method described above. In this example I wanted to use a form with a dramatic curve which changes direction:
I move to the side all surfaces except the one containing the original generating curve (the one I extruded in order to create the surface in the above description). :

I draw a line of any length along the Y axis. Then, using the Curve Length script from <http://kyticka.webzdarma.cz/3d/moi/#CurveLength>, (Thank you Burrman and whoever wrote this awesome script!) I pick up the length of the original curve. Selecting the straight line just drawn on the Y axis, I edit the length in the upper right of the UI,

and position it with one endpoint on the origin (no reason for this move, just for the sake of it):

I then draw a point on the endpoint of the original curve and another on the corresponding endpoint of the straight line of the same length.
Next I select the point on the endpoint of the curve and array it along the curve. For this example I chose 15 as the item count in the Array Along Curve dialog. And I do the same with the straight line. This marks the curve and the line with 15 points of correspondence.
In Front View I draw a series of line segments, snapping one end on each point along the curve, and parallel to the X axis, snapping to the point of intersection on the edge of the surface:

I move the surface back to its position on the form and position 3D View to easily see the each line drawn along the curve and its corresponding position along the straight line.

Then one by one I select each line and move it to its corresponding position on the straight line:


Next I draw a curve using Freeform Curve / Through points, snapping in succession on the endpoints of the line segments as shown:
I select the top and bottom segment and this new curve and Mirror them along the Y axis:

And the result here:

should be a close enough approximation of the flattened surface I was going for and would be used to create a template for cutting a shape out of flat stock. As I see it, the points, intersections and endpoints are all true. The only approximation is with the curve through points. Then again, How many smooth curves can be drawn through 15 points? If I needed greater accuracy I could use 150 points of correspondence. The whole process doesn't take very long at all. As it is, once the sawdust starts flying and I’m straining to see the cutline through badly scratched safety goggles, tiny fractions of a millimeter are not going to matter.
I think I will be able to develop a similar method to “flatten” a surface derived from the surface of a cone.
By the way, Michael, earlier in this thread you described the Perp/Perp snap and the Tan/Tan snap. Incredible! I will be using these all the time. Thanks!
- Dan