I've been wanting to try out FPS Freeks for a while now, to see if they really help with FPS precision, but I don't have a credit card, so I made my own out of some household items, and if you don't have these, I'm sure you can get them, or something similar, with ease.
Step 1: Materials
Okay, you'll need a controller, duct tape, and a certain kind of Krazy Glue (or use any superglue and find a plastic cap or something to use as the "joystick extender").
Step 2: Construction
The construction is simple enough. You rip off a piece of duct tape about as wide as the joystick of your controller, and about twice as long (you don't have to be exact, so don't bother with a ruler). You fold the piece of duct tape in half and use the super glue to make it stay folded (effectively making double-sided duct tape), and stick the tape onto the joystick. Press it on good, then stick the cap (like what is on the end of my Krazy Glue container) onto the joystick. Wrap duct tape around the cap and sides of the joystick to make it more secure.
Step 3: Play.
You now have a dirt-cheap FPS Freek, and you didn't have to destroy another controller and permanently modify another to get it, like what other tutorials tell you to do. It is also completely removable, just peel off the duct tape and your controller is normal again. Enjoy!
(Also, I think I do kind of like this, seems like it really might improve accuracy a bit).
Now, go play Call of Duty or Battlefield or something; you're prepared, now. Just please, I beg of you: don't camp.