When millions of parts are required, multiple cavity molds are justified. Here is a 72 cavity mold for a part that goes into the neck of a bottle to help prevent spilling if the bottle tips over.
Figure 1
Figure 1 shows the part which is about 3/8 inch in diameter and ¾ inch long,
Figure 2
Figure 2 shows the mold assembled..
Figure 3
Figure 3 shows the multitude of parts that go into this mold.
