This is one of my mob grinders that I made And man this took forever just to figure out a effective way to kill them and make them spawn and when i finally found a way to do it, it had already been done well anyways here is my version of my mob grinder made by me.

Give a Diamond?

I have tested for 5 min and in 5 min you get 12 stacks of 64 bones,arrows,gun powder, and rotten flesh.

So that is 5760 items a hour.