Extrude shape with sharp corners

Hi all!

I am to extrude a shape "linearily", that is if there is a 90 degree corner i want the corner to be sharp, the same described in this page: http://blender.stackexchange.com/questions/19709/extrude-along-path-sharp-corners. I've looked at the tutorial about the procedural geometry generetion but this doesnt solve the problem for sharp corners.

Is there anyone with any tips on how to solve this?

Best regards Joel