I just though I'd throw my two cents in. I completely agree with Garry W......... Aluminum tubes are our favourite.... though sometimes we go to brass or copper in extreme currents. They are light enough to cast yet they still sink at a reasonable rate (with fast sink line). They also give a more lively action in the current too.
I'vd tried Loop Bottles out.... they are great for sinking, though I prefer the long tubes since you can have a longer bodied fly and can attach wings without a great deal of skill.
We've been selling tube flies now on the net for a few months.... no tying instructions but there is a few pictures to start from.........