[Zope] - Products with the Lever

I'm playing around with Zope 1.9 final, and am trying to create a Product just for the heck of it. I created a product folder in Control_Panel/Products, but where do you go from there? Obviously, a "Principia Factory" object is required, but what should it be called? What should the method it calls do? I'm a little lost here, and I haven't found any documentation on this. Pointers, anyone?