When you do not need the parts in large quantity, Prototype Mold, bridge tooling, soft tooling, low volume production, pilot production, semi-production ( no matter what you name it) is a great alternative, which is far more cost effective than steel tooling for high volume mass production. It also allows the grouping of similar components within a family tool, yielding greater cost savings. This kind of molds are usually made of softer material, such as: Aluminum, 45# Steel, 50# Steel, P20, etc.

Bridge Tooling for low volume	Soft Tooling to test marketing
Pilot Production for start-up projects	Semi-porduction before mass production