"The LEDs were mounted by using a new (sharp) x-acto knife blade to slice a single small slot in each LED position. I pinned a shamrock pattern to the hat first... The circuit was wire wrapped not soldered. Once all the LEDs were poked through the hat I used copious amounts of hot glue to make them permanent. A 10 kO pot is in line with a 9 volt battery to current limit (and provide a brightness control). A Velcro wire management strap was sacrificed and hot glued in the brow to hold the battery in place."
[Source] RobotDialogs.com
