Throw plaster mould (4)
I believe the answer is:
cast
I believe this is a triple definition!
'throw' is the first definition.
(I know that throw can be written as cast)
'plaster' is the second definition.
(thesaurus)
'mould' is the third definition.
(I know that mould can be written as cast)
(Other definitions for cast that I've seen before include "Personnel in a play" , "Mould; actors in a play" , "In which player" , "characters together" , "discarded" .)