With its presence elsewhere on some of these sabers I would guess aluminum tape
Looking at the other reference where Mark has both hands on the saber makes me think it might have shorter grips to facilitate the clamp being moved lower toward the pommel making the “longFlex” an optical illusion. I don’t know if there’s any history of something like this being noticed but it’s a thought. The tape would then be covering the exposed joint in the Graflex body and whatever they used to secure it.
I eventually want to re do this project, i probably said this before but without more reference ive been lurking
The bolts, if our theory is true (ROTJ Vader Gx is a well used Luke Gx from ESB) then the bolts.. im pretty sure now, are M5 countersunk. My 1/4 20 on the pipe stunt werent sinking well enough for me. I know the bolts stick out on the real prop but the combination of the curvature of the body and the face of the bolt was my dilemma. The prop bolts are obv smaller than the Gx sockets too... so i nabbed some metric bolts with my estimated 9-10 mm face. Modern ones are around 9 or 8. it hit me the other day, where else can we see a bored blade attachment hole?