Also - checkout the LaserTweet Instructable to make this project display data from Twitter:
This project uses an Arduino and some cheap audio speakers to create a real laser show with full X and Y axis control.
The included source code lets you easily draw text and even simple pictures!
View the demo video to get an idea of what this project can do.
You should be able to get most components locally (besides the Arduino).
Assuming you already have an Arduino - expect to spend roughly $35 on this project.
If you can upload a program to an Arduino and solder - you can probably build this project in an afternoon.
Users who have built this project:
mattbeowulf - http://www.youtube.com/watch?v=AnIoWZpEWk8
minhenes (using "real" galvos) - http://www.youtube.com/watch?v=BmYg3O4hlMg
hydronics - http://www.youtube.com/watch?v=5Q3nJLA2t18
benhgd - http://www.youtube.com/watch?v=K23-ThlCZEc
(Post a comment with your link - and I'll add yours to this list)
Step 1: A Bit About Laser Shows
Galvonometers are electromechanical devices that rotate to different angles based on how much voltage they are provided.
A minimum of two galvos are used - one for "X" (horizontal) control and one for "Y" (vertical control).
The laser show's controlling electronics quickly adjusts galvo voltages, and turns the laser on and off - moving it around so quickly that it appears to create a persistent image.
Commercially available galvos can move to up to 50,000 different points each second.
Galvos tend to be expensive - so we'll be making our own out of audio speakers!