Much more complex - to start off just use slush molding and move on when your comfortable with that. Buy a cheap RTV Silicone off ebay and some GP resin and experiment with a few simple bodies and fittings until you get a feel for making masters,avoiding air pockets and gel times etc. You can get very good results using simple methods and cleaning up the cast afterwards. Only move on (and spend more money) when you feel you need a better finish.
Mike