Before I begin I should probably tell you that lasers are not good for your eyes. Don't let a laser beam bouncing off of an uncontrolled mirror hit you in the eye.
I have been mirroring two 1TB hard drives in my PC as a media share for the past several years but my BIOS recently started giving me a S.M.A.R.T. error every time I booted warning me that one of my drives was about to fail. I could have just replaced the faulty drive but decided instead to upgrade to two new 3TB drives and use the old drives as galvanometers for a music-responsive laser projector.
Back in the 90's I came across a device in a music store that was enclosed in a plastic case about half the height of a shoebox that had a mirror connected to a voice coil with a lamp behind a red filter and lens that focused the beam on the mirror so that it produced a red dot that would move to the beat of the music. It wasn't a laser but it worked really well. I don't know what happened to it and can't find it referenced anywhere on the Internet but I decided to recreate it.
I searched the Internet and found several DIY laser projection systems. This one uses old hard drives and a red laser and this one uses hard drives and an Arduino controller to change the color of an RGB laser. I decided to use just a red laser and leave the actuator components exposed.
Step 1: Disassembling the hard drives
A mini Torx set greatly helps disassembling a hard drive.