Every building type produces a specific amount of pet pennies over a set period of time. These values do not change throughout the game. Every building has a progress meter, which shows how soon pet pennies will be available for collection. When pet pennies are ready, a rotating coin appears above the building. Profits do not disappear and remain until they are collected, but new profits will only begin generating after existing profits are collected. Buildings only have the capacity to hold the amount of profit produced in one cycle.
For information on strategy concerning buildings, see Building Strategy.