I believe you're right, BIGREDBUSA. The gun is taped off to cover any bits that you don't want doing, such as a logo, name of gun, detailing etc., and then coated with an activator or etch. The chosen colour of film is placed onto the tank, and the gun lowered through it, I think. Believe it to be non-reversible.
It's my Steyr on that camo post, though it was done when I bought the gun. As said, down to personal taste. I personally love mine, and I have to say, that until you've seen one done, in the flesh so to speak, you can't really appreciate the quality. Mine is a Hydrographics dip. T