I have several times, but just use pellet food right now. Food processor. Get and clean some raw wild shrimp, oysters, clams, squid. Add some sperulina, nori, blanched spinach, and commercial flake or pellet fish food for additional vitamins. You can put it in ice cube trays or a plastic bag and flatten it out and freeze it. You can also add oyster eggs and other diet specific foods. I've heard of people using multi-vitamins, but watch out for copper and other metals if this is for a reef tank.
Just about anything will eat this stuff and it works well for fresh water in addition to salt water fish.
Best bet is to go to central market for the raw seafood. They usually carry everything fresh in their seafood section and you can pick it out individually. They will ask why you're buying small amounts of random seafood though...
Thanks I'm going to try it out