Just my $0.02 here... I did some searching and found a few possible solutions if you go full aluminum hilt and grips. The first is a Rust-Oleum textured spray paint in pewter, and a textured adhesive vinyl.
On close inspection of the Paul Ozzimo renders, the texture is a series of squiggly raised lines similar to the vinyl, unfortunate the vinyl is black and not a dark grey. The rendered texture may be hard to duplicate in any medium. However, I think it would be virtually impossible to tell the difference with the naked eye between the textured paint and the rendering.
Correct me if I'm wrong but does anyone even know if the grip is textured on the screen used prop???
Anywho, I have no problem tending to this little detail myself. I have paid more for an empty hilt than I will be paying for this high quality hilt and blade combined!
Like I said, Just my $0.02...
Paint
Vinyl