hi, I came across the idea of using polystyrene as a moulding tool. what I figured is for certain parts 2 piece moulds might not be necessary. the part can be made out of polystyrene, wrapped with carbon fibre and once set the polystyrene can be dissolved with thinners, leaving a hopefully perfect one piece part. my question is where can I get polystyrene moulding material. im pretty sure I can buy the balls myself off the internet somewhere but that glue is used to hold it together to make boards etc...

You can buy styrofoam board which is extruded so smooth rather than the expanded balls.  Dead easy to pattern from.