While playing with AutoCad a while back, I discovered the offset tool and how it works with polygons. Since then, I’ve wanted a “scale” tool in blender that does something similar. The normal scale keeps angles and relative edge proportions, but the distance between edges is not constant. The shrink/flatten tool, while working with vertex normals, can destroy both. So, I came up with this cumbersome precision tool that does what I want it to: offset each edge a specified distance, preserving angles and edge parallellity (is that even a word?).
It is much more complicated than it needs to be. Oh well, it was a nice coding exercise, and will be easier to expand later.
An example .blend:
[edit: the above link was incorrect, it should work now]
Feel free to post or e-mail me any questions or suggestions.