'Cork, get some saltwater up to a high boil. Turn the fans on and open the windows! (Or do this outside on a Coleman type propane stove). Put the freshest fileted sardines in this caldron for awhile. Use a large serving spoon to skim off the fish oil that will rise to the top. (same with other baits - cold presses are just too expensive; unless you go commercial). You can strain the collected oil thru a porous cheese cloth if you want it pretty and easier to squeeze thru a small bottle nozel. Or you can keep it more natural, which I prefer. If you plan on keeping this stuff around for awhile, add about 1/2 teaspoon of sodium sulfite mixed in real well to extend it's usability quite a while. Combining oils such as sardine and squid or shrimp and crayfish is good to do also, but not necessary. Try adding some anise oil to some of it and Cravex Plus to other containers of it, and compare results on your targeted waters and fish. It's tough to beat fresh home-made scent. ... Also, use the search feature toward the upper right side of the main BB page here to find lots of other good additives to try in your baitoil scents.