Letterworks is right you can model that easy enough, but it's the afterwards thats usually the major hassle. Suppose I'm making a spacesuit and want a pipe running from the rear of the forearm to the rear of the upper arm. So when the arms move the pipe would move as well and remain connected to both body parts. Easy enough to model the pipes onto the forearm, but when the arm moves so does the pipe. Put the figure in a even a basic pose, like a bent elbow, and theres a chance the pipe would poke through the front of the upper arm. OK, you could use a mix of things like easy pose, morphs or ERC. But you'd need to really break the mesh down into lots of groups. It's often the same for non-organic things like Hydrulic struts as well. Which raises the question is it worth the time? Personally If I'm making a static prop or part that won't move, then yes I'll happily detail away like a loon. Indeed I rather do that than modeled always looks better than stuff like displacement. Polycount isn't always an issue either if you're careful. But for moving stuff, I find giving the impression the parts are joined is usually quicker and easier. Which in some ways is a shame as I'd rather try and keep true to my design idea, but equally I know it's about accepting a compromise on whats possible.

Pinky - you left the lens cap of your mind on again.