There are some considerations when selecting rotational mold types to use.
The advantages of a fabricated steel or aluminum tool is cost and a shorter turn around time. Typically, larger parts and less sophisticated parts are a candidate for a fabricated tool.
CAST ALUMINUM MOLDS
When a high degree of detail, complex shapes or a finer cosmetic finish is desired, a cast mold os often the best choice. The cost is somewhat higher.
Without question if you are considering a transition from steel, wire, wood or disposable containers to a reusable containers system, rotational molding is the fastest and least expensive path.