Hi, welcome to my first instructable! I doubt you care!
So let's get to the point shall we?

This scope is mostly made for looks, but it works to a certain capacity, since if you are looking through the scope at an angle, you will not be able to see through it all that easily, but if you are looking straight through it, you will be able to see your target quite clearly.
Though not directly based on anything (it does resemble the generic red dot sight found on the M4A1 and G36C in Call of Duty 4's single player campaign, however), it still looks convincingly realistic.

To build your own, here's what you will need:

Rods:
*yellow = x3
*green/black = x1

Connectors:
*Y-clip = x4
*dark blue 7 clip (circle with space missing) = x10

Spacers:
*light blue ring = x3

Gear Thingies Or Whatever:
light gray closed = x2
dark gray open = x1

Step 1: Lineup

Place all of the dark blue connectors and one of the light blue rings onto one of the yellow rods. Pay close attention to how the connectors are oriented on the rod!
I apologize about the blurry photos, I was in a hurry.
Note: I used some silvery blue parts instead of some of the dark blue ones. Ignore this.

Step 2: Finger Pain

Next, attach the other three yellow rods to the blue clips. Make sure the blue rings are on the rods when you put them on.
The rods are very difficult to attach, so yo may have to get creative in order to get them on. As the name suggests, this step can do a real doozy on your fingers, so I recommend you take a break once you get one rod on, so your fingers aren't too sore to attach the second one.

Step 3: Knobs

Simple step.

Step 4: Finish

And another very simple step to finish with.
Once again, I apologize for blurry pics. If you cannot tell, the parts I am attaching in these final steps are Y-clips. The last pic is simply showing the final product, and no parts are added.