Step 1: Parts
battery holder for 2xAA
Yeah, that is all I used.
Step 2: The Circuit
I got my firmware from evilmad http://www.evilmadscientist.com/article.php/larsonkit
You could always make your own, but the one from evilmad is opensource, and has some nice pwm-ing on it... and I say if it aint broke, don't fix it.
Once you have the circuit working on a breadboard, and you understand how to wire it, move the leds to the perfboard. I spaced them out the way I wanted, and connected all the gnd pins across the top. When I clipped the gnd pins I save the leads, they are needed to extend some of the vcc pins on the leds, because some of them are too short to reach the tiny2313
Put the tiny2313 in the perfboard, pay close attention to the orientation of the chip, and wether you put it on the top of bottom of your target board.
I soldered the leds right to the pins if the tiny2313, the perf board to aligns the leds nice and flat. I used the chip orientation you see in the pictures to make it easier to solder it all together.
2AA batteries = 3V my leds can handle it, and I don't need any resistors.
Last just solder on the battery
Step 3: Video
Some additions would be to add a button, I believe the firmware supports changing the brightness of the leds, but this worked fine for me.
You could also solder in a socket for the chip, so the chip is less permanent, but that is an additional part.
Now go jam this baby in a pumpkin or something!
If you find the instructable is too difficult for you go buy a larson scanner kit from evilmad!!!