Ok, so for some reason I wanted to build a hat with an LED display on it. Lots of them. Hundreds, ideally thousands.
I think this was originally because I was planning to go to the Burning Man festival, in which being covered with lights is a practical way of keeping track of your friends. But the idea was a bit beyond my expertise for a long time, and it took about two years before I found someone who said they would help me with the electronics side and I decided it was worth the risk of buying the kit to try.
I started work six weeks before Glade 2006, i.e. about June. I also optimistically hoped to finish something basic in time, but it took until about February 2007 before I had something which was self-contained and wearable. Obviously not all of this time was spent soldering LEDs, but soldering and testing those and about 400 wires was the biggest job.
Then progress stalled for a while, since I was a bit sick of LEDs at that point, but if I wanted to take it to Glade 2007 I needed to finish it off: some decent patterns and a button to switch between them, which I managed about 4 hours before having to get up again to catch the train there. And it was a success! Despite ridiculously heavy rain leading to a big mud bath at the festival, the hat did it's job without breaking and the most common response was, "Wow, cool hat! Where did you buy it?"
There currently still is only one hat, and the cost of making it is fairly low in terms of physical components, but rather large if calculated in terms of time, since cumulatively I probably spent weeks of full-time graft on it. I do hope to improve on the design (it's a bit fragile currently), and this may result in various other hats or other LED-encrusted things being made. At that point I might consider selling them, although using Enlighted's custom garment construction prices as a guide ($10-$20 per LED) the hat would cost about 10-20 thousand dollars. Obviously it's not currently a consumer market product in it's current form, but maybe I'll find a way to make them more easily in the future.
Of course, if you want to make one and have the time and patience, you can have a look here:
There are some links to LED-hat related resources here:
Finally, some hat movies here: