For the sake of this instructable, just know that you'll see a cool effect where your lasers light is bouncing down a tube!
What you'll need:
A laser - Any colour is fine. I used a cheap green laser pen that I picked up in Shanghai for about 40yuan (4GBP).
A glue stick or some sort of plastic tube
Eye protection - When working with lasers, you must ensure you protect your eyes; especially if you're bouncing the beam around. The protective glasses required vary per laser. Research online based on your specific laser.
What to do:
Wear your laser specific protective glasses/goggles.
Fire the laser beam into one end of your glue stick/plastic rod. If you're using a glue stick, you'll notice that the beam travels through it quite slowly before lighting it up brightly. This creates an interesting effect that looks like a light sabre expanding.
Fire the beam in at an angle so that it bounces off an inside wall. How many times the beam bounces inside your item will depend on the strength of your laser and the density of your glue stick/plastic rod.
Due to the brightness of the laser, it's quite difficult to catch this cool effect on camera. Try it out yourself and you'll be quite impressed at how the light bends to find its way out of the end of the tube.