http://www.ehow.com/how_5091119_make-cold-frames.html
Cheap to make, but might not be durable in wind.
http://www.finegardening.com/how-to/articles/4-ways-to-use-cold-frame.aspx
http://www.todayshomeowner.com/how-to-make-a-cold-frame-to-grow-vegetables-or-flowers/
Replies
This person show you how to build a cold frame. He uses a Thermatic Vent to prevent over heating inside the frame.
How to make a cold frame GardenFork.TV
https://www.youtube.com/watch?v=KIhiCJefPA4
I bought a cold frame about 4 years ago. I have been using it every spring. One the web, a man made cold frame with a crawl space vent. The advantage is that placed at the back of the cold frame at about a few inches from the top, the hot air will escape trhough the vent. I want to try this this spring.