In particular the tools to make the things are separately patentable. It is common to make something useful in the lab, and then a few years latter patent manufacturing tools that enable you to make it. It isn't unheard of for a competitor to find a better way to produce something than you and then you cross license each others patents so both of you can produce the thing but nobody else. (before attempting this consult a lawyer - the rules of when you can make something patented are complex)
