uv mapping question

I made a very simple shape, a six sided cone. My intention was to use a UVmap of it for a paper folding project for some cub scouts.

However, when I marked the seams and unwrapped the shape, the faces were distorted. I ended up switching to Wings and doing the same thing. I would have preferred to use Blender, since it can export the uvmap to .svg that I can load into Inkscape and scale/postion on the paper how I want.

Is there a way to get the unwrapping to create a map with the faces exactly as they should be?

I think I’m having the exact same problem. Just trying to UV map onto a cube and I’m getting a distortion of the image along the diagonals of faces.