This question already has an answer here:
I'm making a guitar, and i found that the easiest way was to make the body, the neck and other few details separatly. But i don't know much about how that affects the render and all that, i think that i have to join them, but the problem is. If i ctrl+j and join them, would i need to join the two meshes by joining vertices or i can leave them like that and is all fine?. And example, here is the headstock of my guitar, i made the cylinders as an independent mesh and i find it difficult to join vertices. How that would affect the end result?