I'm part of a college club and our project involves casting and machining a part. We have solidworks models for the finished product.  However, we need to create a raw casting that will be machined into the final part.  We are planning on using cores for some areas of the casting and I want to use the finished models to make models of the cores.  If that makes sense?  I am having trouble with doing that.  Any guidance would be much appreciated.  I have attached the model.