Smooth, I buy those 3-4" popping corks with the little steel rod through them with the egg sinker and beads already on them. You should be able to pick them up for a couple of bucks apiece or cheaper maybe. Then I usually go with 30 pound test on the leader (I use Berkley Big Game if I have it). You can always add a split shot for extra weight on the leader if needed nearer to the bait. If you're going to be tossing it down at Murrell's Inlet or up at Hog Inlet, I probably wouldn't go over about 4-4 1/2 feet on the leader unless you're wading (at Hog).
I haven't fooled with wire anything in about twenty years since I last made a spinnerbait, so I would not begin to guess the diameter on what that would be if you wanted to make your own, but it couldn't be that difficult, I wouldn't think. IMO, I'd go with the stiffest you could get by with that would pass smoothly through the cork. Along with the wire and the float, you'd need egg sinkers, barrell swivels, beads (on top of the float and on each side of the egg sinker - 3 total).
All that above information is assuming you want the kind of rig with the little steel rod through it, of course.

Otherwise, you'll need to pick up some sleeves and do some crimping.