The tooling cost has two main components – the die set and the machining of the cavities. The cost of the die set is primarily controlled by the size of the part’s envelope. A larger part requires a larger, more expensive, die set. The cost of machining the cavities is affected by nearly every aspect of the part’s geometry.
The primary cost driver is the size of the cavity that must be machined, measured by the projected area of the cavity (equal to the projected area of the part and projected holes) and its depth. Any other elements that require additional machining time will add to the cost, including the feature count, parting surface, side-cores, tolerance, and surface roughness.