Rubies base (Leia's blaster). Cut off the barrel. Added a new longer barrel using a piece of polycarbonate tubing. Used an old screw cap for the nozzle part of the barrel.
Then stripped down a $12 scope from walmart. Sanded, painted, weathered, added scope. Pretty much all I did.
Oh, I did add some heave metal screws into the gun to give it some weight.
Nice. I did a similar thing adding weight with my blasters, because they were originally super soakers and I removed the water container from the back they were extremely front heavy. Got two heavy bolts from my hubbys work with internal torx bit heads that were the right size to fill the gap left in the back that the container is meant to screw in to, cut the extra thread off and glued them in place. Offsets the weight nicely.
