What material would be best suited to make a mould for casting lead?

I need to make a mould from a positive, although the positive has a some what intricate shape which would cause it to be very hard to remove without breaking the mould.

I'm considering plaster of paris, but I don't have any experience with it. Will plaster of paris stand up to the heat of molten lead? Can it be heated to improve flow of the lead into the mould? And finally can it be cut in half to remove the positive without ruining the mould?

There's a thing called a 'search engine'.

UTFSE

Once you've gotten results there, come back here and provide relevant links to sites that detail the process in a manner useful to E&W.

Profit! :)

Casting is easy to find on the web. First, another_number, go here: http://en.wikipedia.org/wiki/Casting and do a little research.

From the article, you should be able to learn enough to then go to Google and do a well-formed search to find a site that can give you all the information you need.

By your post, you will need to look at the lost wax method and the plaster method. You should be able to come up with a combination of the two if the item is very intricate.