worm castings are worm poop. make a worm farm using rubber made tubs with red wiggler worms (ebay$20.00/1000)and feed them things like egg shells veggie scraps news paper cardboard a little dirt and they will make you worm poop or castings whatever you want to call them. real cheap real easy and you get the best soil that you didnt have to buy . 2000 red wigglers can turn into 250,000 - 1,000,000 worms in a years time. then you will need some more tubs and be able to make enough castings and worms to be able to sell them for profit. castingss sell for about $1.00 a pound and the worms go for about $20.00 per 1000. i think it is a awsome idea and kids think its cool , well mine do any way.