Rapid Tooling for medium run
When quantities for prototype or production are in the range of 100-1000 then performing rapid tooling can be a solution.
Rapid tooling can be made with aluminum tooling which is a bit cheaper than steel tooling. It has some advantages: it is usually cheaper than steel mold, slightly faster to execute but have also few drawbacks: the life cycle is quite reduced (rarely more than 1000 pieces) and shot after shot because aluminum is a soft metal, it get eaten by the plastic material and then the mold become less accurate.
For this reason aluminum rapid tooling can be used for parts requiring not too much accuracy and for limited quantities.