thats a pritty decent looking pack…….but if I were you, I would not make the statement “you'll be hard pressed to find a better one” when selling this thing on e-bay. Caus you're gunna get bitched out for makin that kinda statement. As good as it is, it is mostly made out of household objects and is not “accurate to the movie”. the clear tube at the tip of the gun is the least of your worries. I am curious to see how much it goes for though. $100 is VERY reasonable for a pack of that quality. (put another $100 of work into it, and you could put it back up on E-bay for 5 times as much.) I'm not tryin to bash your product here, I just don't think you should give up on it just yet. Your basically done, you just need to put a little more detail into it and you could sell it for quite a bit more.
good luck with it,