I am filing a provisional application for a device that that can be use to improve the operation and performance of a very common item. The device can be designed to be integrated into the design of the item (i.e., a manufacture could produce items that have the device as a built-in feature) or designed to be added onto an instance of the item not originally designed to utilize the feature. Imagine a special handle that makes it easy to carry a box and a box with that special handle designed right into the box. (For clarity, my invention has nothing to do with boxes... it's just an analogy. ;) In the provisional application, I describe embodiments of both genre, i.e., as an independent box handle and as a box with the handle designed right in.
My question is, if I move forward with a full patent, will I be able to file more than one patent referencing the provisional, i.e., one for a handle that can be added to a box and one for a box designed with the handle built right in? Is it enough to patent the handle and just assume that no one would be able to build a box with the handle integrated? I know there are a lot of "it depends" conditions and that's fine. I'm just looking for general guidelines on what's possible and what's likely.