I personally use raw shrimp (deshelled and cleaned of course), clam, mussels, oyster (if you can find some really fresh ones), selcon(if you have it), throw in some frozen mysis shrimp and fortified brine shrimp. Make sure you rinse everything in purified water first though and cup it all in smaller chunks so that it is easier to blend. Add a little RO/DI water into the mixture and start your blender. Only run it for a couple minutes then pause for a minute and then again for a couple minutes, this is so the mixture doesn't get too heated and get cooked. Once it is nicely blended, I put the entire thing into a large ziplock bag, flatten it out and place in the freezer to freeze.
Jonathan may have some other ingredients he uses as well.