I use a length of 1 1/2 inch pipe weld a plug in the bottom then cut it in half and weld flat bar on the sides and bottom so it locks it together i just drilled a hole at about the 32oz line then if you want biger just let it cool 10 sec and continue pouring i just use some tig wire in the lead

You could just use sand and put a wire insert in them. Just make sure you don't use wet sand.

Hi Joe

Not sure that the plaster will take exposure to the heat  without breaking down .

What about using modelling clay ?

Plaster will take the heat, just it has to be bone dry or there is a very real risk of serious injury.

Look up casting sand, its a very safe mix of  sharp sand, clays & hydrocarbons. You just tamp it into shape, make sure its dry, then pour.

if u want to make staf sinkers just use yellow sand. and press in images with the sinker. Obviously the sand needs to be wet and let go hard prior to pouring lead in.

we used sand as kids, use wet sand to form a mould then wait til it dries then set some good wire it the mould and pour away

Anything aluminium works as a mould.  Beer cans, ali tube, berocca tubes you get the idea.

I used plaster of paris as moulds as a teenager, mostly for bean and ball sinkers, and it works fine but eventually becomes brittle.  I suspect that the heat generated by large snapper sinkers will accelerate that.  As already stated, make sure the moulds are absolutely dry before using.  Because plaster of paris is pretty porous,  it may be a good idea to warm the moulds for a little while in a kitchen oven to make sure they are dry before using them in this damp weather.

Peter

i also had a look on the net by googling home made sinker moulds,and one site suggested copolymer modeling clay,i was wondering who can i buy the copolymer modeling clay from? thanx crew for your imput so far,big thankyou guys

Further to my earlier response you can pour lead into any shape you choose to chisel / router out a shape in a piece of timber.  Chars initially but then it's all good.