Go to an automotive tire store and buy some used tire weights. Any old
scrap lead will do.

Melt the lead (do this outdoors) in an old pot, and pour it into a mold
that you make. Make a sounding lead shape using wax.
Make a mold for the lead using 'cement mortar mix' from home depot etc.
with the wax 'image' inside it. Mix up the mortar mix with only enough
water to make the cement 'barely stick together' - 'ram' the barely wet
cement together ... to form a mold that easily breaks apart.
Put the mold in an oven inverted so that the wax melts and runs out the
mold, heat the 'weak cement' at 300 degrees for at least 8 hours to
drive off all moisture in the mold.
Heat the lead in an old pot until it melts (do this outside to prevent
breathing lead vapors)., pour the lead into the mold and let cool.
brreak up the cement mortar mix carefully so as not to also break the
lead, trim the lead to remove all imperfections.

If the tire store wont sell old lead tire balancing weights, buy 4 ox.
fishing sinkers from a fishing shop and melt them, etc. Any old scrap
lead wil do.

Hope this helps.