the theory behind a heat pipe is very simple and well documented, no need to take them apart. Also, you'd probably not be able to tell what it does without seeing it in action.
Basically a heat pipe is a closed circuit phase change. the liquid at the bottom heats up enough to vaporize, then it cools at the top, and condenses down the sides. Heat is transfered from liquid to gas side. There are many techniques used to increase the efficiency. One of the most important parts is to have wick material, so the surface "wets" better. That's about all I can remember for now, but try googling for information about it. It's very simple.
I have seen many heat pipes used in horizontal orientations e.g. zalman 9500, TT typhoon, even the AMD dual core cooler. However, I have yet to see a upside down heat pipe. I suppose if it was doable, they would have done it already. The liquid has to stay at the hot end, so i'm not sure what you could do... Perhaps a cyclic design or one with a pump? Sort of loses it's elegance, but I suppose it would work.
As for making a heat pipe. Well it's extremely difficult. The wicking material inside is actually designed to decrease surface tension I believe. Even with a large amount of manufacturing machinery, I doubt you'd be able to come close to the performance of a commercial version.
BTW, don't try using the ones that screw on or anything. Commercial heat pipes are cold-treated then placed into the joint and heated (so it expands). Quite an efficient solution, but unless you have vats of LN2 sitting around... it'll be hard.
Heat pipes are also designed for only a specific temperature range, so find out what you would need to incorporate into the design for that specific temperature.