I thought it would be fun to add LEDs to my brother's Constable hat so it appeared to look like the light bar on a police cruiser.
Step 1: Materials
There are a lot of wearable electronic materials available. I ordered LEDs, Arduino and battery box from AdaFruit and so far have been happy with the products/support. To complete this build I used 30 ga wrapping wire and plastic canvas to hold it all together.
Step 2: LEDs
I made sure the plastic canvas was a good fit and then used its grid to align the LEDs and wire. The wrapping wire was easy to thread through the canvas and electronics. I didn't strip the wire anywhere and used the soldering iron to heat the plastic coating a little when soldering the connections. In some places I didn't get a good contact the first time but by applying more heat I was able to get all the connections secure. I even soldered a few of the LEDs while the circuit was energized so I could confirm a good contact.
Step 3: Hat Modification
The LEDs were visible behind the hat material but barely. I used the soldering iron to burn holes in the hat surface near the LEDs. Now the light jumps right out as it should.
Step 4: Display
If you see this hat coming towards you, remember to pull off to the side of the sidewalk! Thanks for looking...
Step 5: Code
There are many ways to code LEDs flashing. Here is my source code if you are interested.