Hi Gavin,
Thanks for the suggestion and link. I have tried this plastic drain pipe and I found it worked quite well. You have to get the biggest piping you can and make sure you have wire, or pegs to anchore it down. I certainly found it retained the fine material and the larger material rolls through easily. Mine was a bit longer (about 1.25m) and I found I could get through a large amount of material in an hour. It certainly is very light (I didn't use velcro, just tied some twine around it) and it didn't take up much room in my pack - excellent for taking into the back blocks.
Thanks for the tip,
Cheers, Ian.