What is the best way to have machine parts duplicated and produced?

I have a friend who has a model of a robotic project he has been working on for over a year. All the parts to this project were made by him by hand out of steel, aluminum, wood and polyethylene materials. He is getting to the point where he needs to document and patent his project for production of some orders he wants to fill. I am not a machining expert and do not have a background working precisely with these materials. I know these parts need to be reproduced precisely and accurately. Probably more so than his model even. But he is afraid of the design being copied or stolen if he brings them to a machining shop to be made. He may even find he has some good suggestions on changes to make on his project, like I have already made a few to him. Any suggestions or recommendations I can make to him for help?