Typical patents are for ideas and concepts, though there are different classes of patent that covers industrial design, brand identity, etc. Patents can very well be broad-based, and cover a wide range of things. It all depends on the type and the claims stated. In engineering, patents very much cover an idea - and do so in blanket fashion, within the scope of how they were worded. Others (usually newer) patents cover a very narrow distinction, typically in ways that set it apart from older designs or competitors' products. If you have free time, study the case of Ford vs. Seldon, or more interesting, Curtiss vs the Wrights. Those are both cases that the patent claims were so broad based, that any sort of vaguely similar idea was (initially) considered infringement. In this sort of patent, you would not be issued a patent for a nose cone that you designed, unless you could demonstrate that it was functionally novel or unique and did something no nose cone before had. Or you applied it to a different type of product that it was never used before.
Patents that deal with form of design, styling, logos, etc, are specific to the actual form and shape of the item in question. This is where proportions and appearance matter. This is why Jeep sued Hummer a few years back for the 7-slot grill, and why automakers all around the world struggle with designs copied by Chinese manufacturers. So, there a lot of different ways patent questions can be considered. Such blanket statements alone aren't that simple.
What I have been told regarding cloning rocket designs is as Roger indicated. OOP designs can be copied by other manufacturers for sale. However, individuals can clone all they want for personal consumption. Current production designs cannot be copied for sale by other manufacturers.