A stockpile only has a certain distance it can be connected, and items moved between them manually.

It would be cool to be able to build a building that connects two stockpiles so a player could, for example, place items in Stockpile A and over time all the items there get moved to Stockpile B.

At first this could be mechanics, and requires calories to be put into the conveyor belt system. It would be fairly slow (1 item a second?). Later, electricity could come into play and it would be much faster, with end-game tech giving "smart-conveyor belts" that would only move the items specified.

This would be useful for those large storage areas and production chains.