I have a couple of last tweaks I want to make to my hat, that didn't make it into this tutorial. 1) Add a solar panel or two to the top, for self-c...
Top hats are cool; just like bow ties. Not only are they stylish, but they give you a lot of room for incorporating techno goodness. I recently had cause to buy a tuxedo, which necessitated a kilt, and then a top hat. You know how it goes. To the tux I added silver buttons, the kilt was exemplary on its own, so only the top hat needed some flash. I decided that since my head is generally in the stars, I should try filling my hat with stars. Initially I was going to use an arduino and some 1W white LEDs hanging off the PWM lines, and feeding the light through fiber optic lines, to create a twinkling effect. By the time I started work on the project I realized that I wanted colors, and that 1W LEDs were going to drain my LiPo battery pretty darn fast. Multiple color LEDs on a single arduino is a bit of a problem, though. There are only six PWM channels, so I would max out at two RGB LEDs. Fortunately I had a few sample Total Control Lighting control chips from Cool Neon in my kit, and with a little hacking they are perfect light sources for this project. Each TCL chip is a latching, addressable, three-channel PWM controller; so I can control a near infinite number of RGB LEDs from a single arduino. Hat space is limited though, so I settled on four; that provided sufficient variety. The end result of my project is a super-stealth techno-mage top hat that looks amazing when it is turned on, and completely normal when it is turned off. I can wear it to Dicken's Chrismas Fair and nobody will notice, or to That Thing In The Desert where everyone will notice; one hat for all occasions.
I built this project on-site at Burning Man, with only the tools and parts I had in my travel kit. You should be able to complete this project in two days, accounting for glue drying, using easily available parts for less than $200.
tl;dr This article will walk you through every step necessary for adding multi-color dynamic fiber optic lighting to your hat, or any other project to which you want to give a star field effect.