I'll generally use a size 7 snap for my lead cinches. I usually use about a 1 inch piece of tubing speared by the snap and then close it. If using a good quality snap swivels (Rosco is what I'll use, they are marketed under different brand names, but all stamped with 'USA'), I'll attach my mainline to one end of the swivel and the leader itself to the snap. I wouldn't dare do this with the twisted brass swivels, they don't have the durability that the good ones do. I like to attch this way so that you don't have the snap portion dangling ... it tends to twist up on your line more often than the way I usually do it.

Most shops usually carry it in our area, but Cabela's might be a good option for you ... I'm sure you could do a search to find bulk tubing on line.

BW's method does work fine with one major drawback ... the surgical tubing method does allow for much easier changing of the weight, which for me is important as we're usually on the move