The model for this mic was produced with NC machining from model wax and aluminum. 3D printing will be used for the next batch. The cost is roughly equal but obviously printing makes it possible to produce the whole model in one, i.e. no need for separate inner and outer models. For single pieces I would recommend wax print master, but it is not cheap when done with good accuracy. When the aim is to cast more than 2 pieces, it no more makes sense to print the wax directly, and an intermediate model is needed, which then is copied through silicon castings. This phase is the really difficult one.