Jatropha is grown on plantations for bio fuel, after harvesting the jatropha a nut press is used to extract the crude jatropha oil from the physic nuts produced by the jatropha plants. Any simple worm gear press will be able to extract the crude jatropha oil from the jatropha nut.
Out of all the various machines that I have seen to mechanise the process of extraction of the oil used for bio fuel from the jatropha seed this is the best one!
However in rural Africa and other poorer parts of the world I feel a hand operated screw press is the cheaper and better option. Using the machine takes work away from the villagers!