Thanks for all of the suggestions. I've used the epoxy/lead shot method before, but I didn't like it. I've decided to go with the "melt-my-own-and-mold-it" method using lead shot and an inexpensive lead "furnace". I expect it will be cheap and relatively easy in the long run. I was having trouble locating a supplier of the material, though, but I have that solved thanks to the suggestions here.