I know this has been kicked to death but I have another idea for the screening material in a rectangular cooler. Because I like building things myself I am going to try several differnt screening media just to see how well they work. I have been reading the threads here on building your own and it is easy to see what does and what does not work.
Here are two ideas I am going to try.
1. a pvc water well screen pipe. They can be purchased in different diameters with the slots beginning as small as .02 thousands on up to 1/8 inch slots. To see a picture of the pipe screen google "pvc water well screen" under images.
2. I have a large sheet of stainless steel screen that is fairly rigid with the holes or openings approx 1/16 to 1/18 inch. I plan to build a framework for it to sit down in the cooler just above the drain valve. It is rigid enough to hold the average grainbill I think. I may also use this screen sheet in conjuction with the standard copper manifold.
I know there are other EASIER ways to to this but I enjoy the DIY part of this almost as much the actual brewing. Besides, I already have these materials on hand for free :^)