I am in the process of making my first swimbait, a 4" crappie, out of birch. My process was to cut center line slots in the top and bottom, leaving about 7/16" in the center. Then i rough carved. Next I ran ss wire hinges through top and bottom and epoxied them in. At this point, the final carving and sanding were done. I sealed the bait with superglue. This left a slot in the whole length of the bottom of the bait a little less than 1/8" thick (Marathon saw blades are thin). I squashed some solder with a pair of vise grips and friction fit it into the slots. This allowed me to move the weights around, tweak the amount and water test for proper action, sink rate, and attitude. Finaly, they were glued in and the gap was filled with epoxy and micro-balloons. I don't know how others do it. But this seemed like a great way to tweak a bait. I am very happy with the results.