Jazz, my apologies. having read a few different posts on the subject I obviously picked up what you were saying incorrectly, easily done on the internet I think. As for supported round rail well I had looked at that but it seemed to be a bit expensive as well, never considered buying in from China as I know people who have had their fingers burned doing just that. Problem with buying in from China (well how I see it anyway) is that for every good supplier there are two or three that you don't want to go anywhere near & unless you know exactly what you are doing or have recommendations from people who have actually dealt with a company over there then there is a good chance you will get it wrong. Can be a very expensive learning curve & one that I would rather not take.
That's one of the reasons for me joining the forum in the first place, knowing next to nothing about a lot of the components used & where to source them the best place to go is to those people who have already done it.