This is a mini-fig sized gravity gun from half-life 2.
Step 1: Pieces
You do not need both transparent bricks if you are only making one gravity gun.
Step 2: Assembly
Replace the orange piece for the blue one to make the supercharged gravity gun.
Step 3: Mini-fig Use
The dark grey claw piece needs to be angled slightly for the gravity gun to fit in a mini-fig's hands correctly.