Ok so we have a competent cnc machine shop but have never made a investment mold. I know we have to take in account shrinking and venting but what else do we need to understand? I have a investment casting house ready for tooling but I dont want to come across like a complete ass. This is a rookies attempt at a investment mold. We are lookign at 356 aluminum and using a basic 6061 mold for the wax