Gnome Farms. One in Journey Mode, one in Master Mode, and one "eXperimental" world. The eXperimental world is a Master Mode world that has its time frozen at 12pm noon, and its spawn rate should be increased.
To use the farms, your character stands in the box they spawn in, flip the lever, which activates the timer, and let the gnome statues come in. The switch de/activates the blocks once. Don't replace the timer, as slower allows gnomes to attack your character, and faster won't allow max spawn rates.