EPISODE VI: RETURN OF THE JEDI
Used by: Princess Leia (on Endor)

   
This blaster prop was created from a Margolin .22 MTs target pistol manufactured by Soviet arms factory. The same model was used to make the DDC Defender used by Princess Leia in Star Wars: A New Hope. 

Margolin .22 MTs Target Pistol

The ridged section of the barrel is believed to be made from parts of a plastic model airplane engine (4 halves glued together).

Model airplane engine part

The front sights of the gun were left unmodified. The very front piece is a different muzzle brake than is commonly seen on the gun, but it may be a variation or interchangable accessory for target shooting.

On the right side of the gun 4 squares were added to cover up serial numbers and other text on the gun. These may be black rubber multipurpose protective squares (most commonly used as "feet" on objects so they don't scratch the surface they're sitting on) or possibly from the alliance rank bars used in The Empire Strikes Back.

The prop photo shown at top is most likely a resin casting of the final prop. It would be used as a lightweight alternative to carrying the real gun which fired blanks. Shown below is a detail shot of the gun in the movie just before Leia shoots two stormtroopers outside the Imperial bunker. Note that the squares added on the side are not multicolored like the one above. This one is the blank firing "hero" prop used for closeups.

Still frame from Episode VI: Return of the Jedi