I'm finally going to have a worm bin that is EASY to use. I am not sure I agree with this website when it says that castings will drop down, though. I think you have to rotate the layers, harvesting the bottom each time.
Earthworms are amazing garden pals – and powerful composters. Learn how to harness their talents by vermicomposting, and start your own home DIY worm farm! http://gardenerspath.com/how-to/composting/worm-farming-vermiculture/
Raising Nightcrawlers could be one of the most meaningful things to do especially when you are not busy. Aside from the fact that they are both good as composting worms and fishing baits, they are also very adaptable making it easy for you to raise them.