Triangular Bee Escapes

Hi All,
I was wondering if anyone knew how to build a triangular bee escape. I think that this would be a great addition to the plans section of this website.
Also, has anyone used them before - and would you share pros and cons of their use???
I currently have only 2 hives (if they make it through the winter) and am considering trying these escapes. Frankly, I tried the elliptical escape that fits in the inner cover and have found it to be useless. Maybe I didn't use it correctly.
Anyway, whatever help you can send would be appreciated.

Thanks,
Paul