You guys mirror my experience exactly. I got my first ar in '96 and for many years losing brass was a reason not to shoot it, especially in the snow.
To continue with the story, a few weeks ago I had a "eureka" moment and came up with one different than I've ever seen. I've made several now and they seem to work. I have tested them several times at the range with no failures of any kind, but have not been in the field. They are made entirely of pvc fence material, so are very light, and $8 worth of material was enough to make about 8 or 9. It does take a few tools and a little time, though.
The catcher design itself was easy; designing a way to mount it to the rifle is the hard part. So far I've got a good way to mount them to my two designs of uppers, the dpms high-rise and a regular flat-top with regular weaver style rings. Using one of the Burris or Larue style mounts would require another design, but would be doable if I had access to one. The same applies to the a2 upper. If I can figure out how to get pictures from my camera to here I will if anyones interested.