Parts that are expensive to manufacture. Parts with complex geometries, for example, might be less expensive in additive manufacturing. Simkin's example was a part GE produces based on a stochastic or variable demand. Since they must produce the part in small, odd batches, each order can have a high cost per unit. Additive manufacturing stabilized costs and kept the price per unit low.

Long lead time. If long lead times are killing your ability to meet demand in real time, a solid additive manufacturing process might help.

High inventory costs. If you can't afford to store parts, print them as you need them.

Parts sole-sourced from suppliers. If you use a specialty machinist that goes out of business or is acquired by your competitor will your business be seriously hurt? Additive manufacturing can work like an insurance policy, managing your risk.

Remote locations. Need parts on an oil rig or on a battlefield? Make parts where and when they are needed.

High import/High export costs. Costs added by import and export fees can be eliminated by 3D printing.

Improved functionality. Can't get what you need? Design and make it yourself.