I do raw shrimp, scallops, squid, mussels, crab, cod adn a few wetted sheets of nori.
Put it in the food processor and blend it until its pasty.
Then I put a piece of eggcrate down on a cookie sheet covered with aluminum foil and I pour the paste intot he holes in the egcrate.
Put it in the freezer and let it harden up a bit then take off the eggcrate and empty the cubes into a gallon ziplock bag.
If you buy it from a seafood store it's about 10 bucks for everything and it lasts quite a long time.
Mine actually ends up becoming a little freezer burnt by the time I get about 3/4 of the way through the bag. ( Probably about 3 months)