Step 3: Everything in place
Now you are going to need to make sure that your LDR and laser are not going to be moving around while you're testing the rest of the software.
I used a hot glue gun and used a small amount of hot glue on each edge of my arduino board to secure it to a plastic cassette case, (a piece of wood and some screws would be ideal but I didn't have any) The hot glue should be removed easy and if it doesn't it's in an unimportant location.
I then hot glued my laserpointer onto the platic cassette case and rested it against the arduino's digital headers. The LDR doesn't move around so I didn't have to worry about it moving. Your set up may vary but you get the idea.
You'll then want to make sure the whole thing won't move around, I used sticky tack on the bottom of the cassette case and put a jar of change on top of the USB cable so that it would not move around while testing.
You'll also want to affix your mirror to something, it's up to you to figure this one out I used sticky tack to adhere the mirror to an old and heavy Kodak brownie camera and set it on a stool with a few books on top while testing everything out. Later I just affixed the mirror to my camera tripod.