This is what my version of Gordon and his gravity gun look like. Like the portal gun, the was based off the design of kooberz, but modified.
Step 1: The Weapons From the Game (legofied!)
These are some of the weapons that I used. Funnily enough, the pistol and handgun used in the gravity gun are two of the guns in the game, so that should be helpful for lego movies.
Step 2: Gravity Gun Parts
These are the parts that are used in the assembly.
Step 3: Gravity Gun Assembly
This is pretty straightforward. Make sure you put the handgun handle facing forward, which looks the best.
Step 4: Gordon Minifig
These are the pieces I used for Gordon. I put the holder at an angle so it would look cooler.
Step 5: Posing
I made a play set with all the bad guys for HL2 after him. To put the barrel in the air, I placed one of those clear bricks under it.