To get started light sculpting, you'll need a camera capable of long-exposure photographs, a tripod (or a very steady friend), and the Penki app itself.After a brief and excellently-illustrated tutorial, you'll enter your text and see in real-time how it will ideally look in the finished product. You can also choose from a treasure trove of Space Invaders-style symbols, in case you're alien-inclined. Choose from a variety of colors or gradients, set your timing, and you'll be told how far you need to drag the iPod for the exposure. Hit the "paint" button, trigger the shutter on your camera, and move the iPod across the its field of view -- then check your results.After each exposure attempt, you'll get a full report on your performance. The accelerometer tracks your steadiness and gives you a percentage grade, along with a cheeky comment like "Rock solid!" for a good performance (maybe you slid your iPod across the table), or "Shaken, not stirred" (you were jumping on some sort of trampoline). You'll also get a 3D graph of exactly how you moved the device during the attempt, a location-aware map, and the option to share your report via Flickr.It's certainly not easy to get this completely right the first couple of times you do it. If you're trying to make a readable series of words it takes a lot of trial an error to even get all the letters to appear in the frame. Moving the iDevice so precisely in relation to the lens is often maddening, and sometimes you really have to focus to keep your hand out of the frame. You've also got a lot of settings to play around with, both in your camera and in the app -- exposure time, ISO, f-stops, white balance...all things that will make or break the readability of the words.But you've got to think about it -- you're painting with light. It's like having a new super-nerdy paintbrush for your already-nerdy world, so why try to be precise? The most fun way to use this app is with a heavy dose of impressionism. Why not try to illustrate your cat being chased around the room by aliens? Draw some arrows hopping up the stairs? The worst that can happen is your picture won't turn out. The best that can happen is that your cat gets chased around by aliens, which is awesome.We have a couple of small gripes with the interface: you can't turn the timer volume off, even if the system volume is all the way down, and we found ourselves accidentally navigating to the home screen far too frequently. And it would be nice to be able to see your target path length in inches, not centimeters. Yeah, we prefer Americanized metrics -- what of it?But at 99 cents, this is some truly next-level stuff, and we're definitely willing to forgive Dentsu London for these pecadilloes in exchange for a mega-awesome 2.0 product. We can't wait to see what they come up with next.In case you missed it the first time, here's the original concept video: