Sometimes it's cool to put your building skills to work not to create an object to serve a practical purpose, but to sit, undisturbed, impressing the hell out of anyone who happens to see it. I'd say this replica Arc reactor (featured prominently in the Iron Man series of films) is the perfect example of crafting raw awesome to bemuse your friends (and drive them crazy with jealousy).
An Instructables user by the name of "Duck210" is responsible for this authentic-looking recreation. Put together piece by piece out of aluminium, copper, LEDs and some "scrap" PCB, it does everything you could want from an Arc reactor, except perhaps produce vast quantities of clean energy.
It glows though!
I'd be pretty happy with how it looks now, but according to Duck210, there's still a bit of work to do, including installing connecting wires between the coils. Depending on how much work was involved and the difficulty of construction, I'd get a little assembly line going — I'm sure there are plenty of people who'd snap up one of these without a second thought.
The hard part? Installing it into your chest (and forging a metal suit to go with it).