I posted a story of how to build a Manitoba fly trap in July of 2010. I had to make some changes and I wanted to bring those to your attention.
I ended up changing out the flimsy plastic to a combination of 1/4 plywood and screen fabric. It is mcu more sturdy and works very well. However, it is heavier and I had to bolster the legs because they started to crack under the increased weight.
(original story is at http://rreflection.areavoices.com/2010/07/01/project-fly-trap/)