Source: Wookieepedia
The original hilt carried by Mark Hamill in Star Wars: Episode IV A New Hope was made from the flash attachment of a Graflex 3 cell flash unit, a flash tube attachment used on forties-era press cameras, with the ridged grips made by gluing portions of hard plastic T-track used for cabinet sliding doors (often mistaken for wiper blades) onto the bare cylinder, and the switch plate fashioned from the LED display of an Exactra 19 or 20 calculator. A D-ring assembly was also added to the bottom. The lightsaber used in Star Wars: Episode V The Empire Strikes Back was again based on a Graflex, but the ‘T’ tracks were instead screwed on, the switch plate was replaced with part of a circuit board, the Graflex logo was covered with mylar tape, and part of a Kobold camera flash was used to created the D-ring assembly.
For Star Wars: Episode VII The Force Awakens, genuine Graflex flash units were used to make the lightsaber props. They were based on a hybrid of the A New Hope and The Empire Strikes Back versions, as they feature the « glass eye » and « beer tab » top half parts from A New Hope, and circuit boards and ‘T’ tracks attached via screws bottom half from The Empire Strikes Back. To hide the Graflex logo, a « wrap » was created that covers most of the flash unit’s clamp. The clamp appears more golden colored in The Force Awakens.