This project is a variation of the work of yergacheffe at the atomsandelectrons blog. I wanted to create a Valentine's Day present for my wife, and thought a nice edge-lit sign would go over well.
On his recommendation, I tried out some octobrites from macetech. Although I have some experience with arduino and other electronics projects, I quickly realized I would have to really dig into how the octobrites work in order to achieve the effects I wanted. I didn't have that kind of time, Valentine's Day was quickly approaching, so I decided to go with an array of 10 Ultra-bright white LEDs available from adafruit.com. I used the LED Array calculator to determine the resistor values for the array. Note: you need to know the Forward Voltage value and Foward Current value of your LEDs to use this calculator, but that is easily obtained from the LED data sheet.
I used an adafruit Perma-proto full-sized PCB as the base for the array, cutting the board in half length-wise to fit. I used a Dremel-like rotary tool to cut out the base and shadow box of an IKEA picture frame as yergacheffe did. I was surprised that I was getting smoke off the material as I cut it. I used fluorescent red acrylic, 1/8" thick cut on a TechShop Epilog Laser. The actual heart logo was clip art I grabbed from the web, then did some smoothing in CorelDraw. I used the trick yergacheffe discovered of mirror-etching the sign on the front of the acrylic, then mounting the sign reversed so the text was the correct orientation and was brighter. Good tip!
Finally, I added a switch and a 5V voltage regulator circuit. That way, I could use either a battery or wall power to light the sign. The result is a bit dim, even on wall power, but where my wife has placed it, it's plenty bright.