It doesn't smell that bad. Cook a pot roast or something at the same time if you're worried about the smell. I make it with chicken and beef bones I use for making Pho. The beef bones can be hard to grind up but the chicken bones end up nice and crispy to where you can crush them with your fingers. I don't roast them until they're black or anything. They just need to be roasted and dry. I make my own meals these days as I don't like to waste anything. It doesn't take much work at all. No need to buy something you already have. I save all my eggshells as well. I also make my own tofu so I dry the okara that's left over which is basically soybean meal and a good source of nitrogen.
Left is WCA and the right is WS-CaPo.
Cho Global Natural Farming, SARRA India
www.cgnfindia.com