On Sat, 2 Dec 2017 01:35:12 +1100, FMurtz wrote:

make the weight shape with a sprue out of polystyrene cover it with
plaster of paris and let completely dry
and bury it in very dry fine sand.

That'll work if you place the plaster of paris in the oven and heat it well to
dry. Otherwise, the faintest trace of moisture in the plaster will turn to steam
and spatter lead all over the place.


Thomas Prufer