Hi, all. I used an Arduino Pro Mini 3.3V and a WT588d to create a custom sound board and LED controller for my lightsaber. I love this little board. Special thanks to SugarBombs for sharing his working code for the WT588d module! http://forum.arduino.cc/index.php?topic=227435.0 That really saved me some trouble.
Here are video and pics.
Core IC components: Arduino Pro Mini 3.3V, WT588d sound module, some small MOSFETs, and a 5V regulator.
Components mounted on some perf-board and inside the hilt.
And here is a video of it working: http://youtu.be/3PacAFmnF_8
Update 1-29-2016: If you are interested in building your own, please read this thread in its entirety before posting questions. You will find that it is a trove of useful information. Most common questions have already been answered.
Update 8-18-2016: For help in creating your own Arduino saber sketch I have created the Universal Saber Library which supports various hardware. The most recent version is available on GitHub here: https://github.com/JakeS0ft/USaber