Simple box with a tight fitting lid, I use it to breed earthworms for fishing. I'm sure you can use it to hold something else if you were so inclined.

Lid has holes both for breathability and because light will keep them from trying to escape.

This size can maintain a steady population of 60-70 and they will breed rather easily (speaking on red wigglers, night crawlers would probably have a lower population).

Occasionally I throw some chia seeds, lentils, oat bran, or veg scraps in there for feeding. Coco coir is kept very lightly moistened.

There are other earth worm farms out there more focused on composting, because this one does not have a drawer system and is a glorified plastic box, the substrate will need to be changed out approximately every 6 months ago to prevent too much build up of worm excrement making them sick (speaking from experience with isopods, this may be completely wrong).