[Flieger]

You can use strategically placed "risers" that are reserved of metal to account for cooling shrinkage. The gating system must be engineered so that these are the last places to cool.

A cool technique is "lost foam". You make a pattern for the part and gating system out of foam, coat it with some special, permiable refractory coating, and stick the whole thing in sand. Then pour the metal right into the foam. It is much quicker than lost wax and does not need so much special equipment for the sand mold making since the sand is just loose and supporting the shell around the foam. You can make much more intricate details that way, too.