Was running out of ideas for a Halloween costume, and fell back on the old standby "Mad Scientist". I mean, I have all the stuff already

Actually I had the lab coat and magnet already. The idea was to hang out next to the line for the Insane Clown Posse when they had a concert in town, around the time of the whole "Miracles" meme. I built the giant magnet out of two layers of 2" styrofoam insulation panel from Home Depot. Did not have a hot wire foam cutter, so I made one by running about 20 amps through a piece of 28 gauge magnet wire.

So I wanted to use the magnet for the mad scientist costume this weekend, but thought it needed a little more pizazz. Also, some bracing across the ends so it wouldn't get crushed and broken. A piece of clear acrylic seemed like a good idea. Then, I realized that the acrylic could have more than just a structural function. I called up
TechShop and reserved some laser time, and etched fractal lightning patterns on three panels.

I also cut some notches in the ends to fit a 100mA, five-chip blue LED (same as used on the
MegaBrite). A little acrylic glue bonded the LEDs in place and they sidelit the fractal design extremely well.
Next, I cut slots and pockets in the foam, and mounted the panels and an
Arduino Uno,
ShiftBrite Shield,
ShiftBar, battery pack, speakers, and audio amp.

The result is pretty fun, if a little unexplained why a magnet is throwing off sparks (how do they work?!). Well, magnets would be even cooler if they did, I think. Less useful maybe. Anyway, here's the video of the finished product. The audio feature was last minute, so I had to start using duct tape...the actual sound could be tweaked a bit too.
http://www.youtube.com/watch?v=L6UlE1NH4iQ