Correction on a few of the points raised:
IIRC, Dooku's AotC was actually made in metal. Likely made from machined aluminium stock and (possibly) cast aluminium parts for the main hilt segments. The whole hilt, but the "knuckle" segment, has a polished metal finish. The prong that runs the length is aluminium. The one's made for RotS are resin casts off of this piece and vacuum metallized/chromed. The Hero AotC hilt was in the private possession of Christopher Lee in a bank box before he passed (don't know where it is now) and the chromed resin Hero for RotS was recently auctioned off by Nick Gillard.
Palpatine's RotS hilt(s) were made last-minute on production, literally while filming. Anakin was originally supposed to fight Windu, then it was Palpatine fighting Windu with Anakin being a wallflower, but then Lucas changed it last minute to Palpatine only and the thing was quickly designed and produced, essentially, for inserts. Palpatine still fights with Anakin's skinny-flex stunt during the sequence with Windu in every shot but for the close-ups of the hilt at the beginning of the fight, and the cg shot of it flying out the window. It's likely that the whole thing was 3D designed and printed, cast, and vacuum metalized, too, just due to production needs. They had enough time to make a number of them to get the color finalized as there have been a number of prototype pieces appearing over time in the wild. The MR is still the closest to accurate, IMO, but the color is inaccurate for both the hero and the V2. In that regard, there's not been an accurate Palpy hilt made and every replica made off of the MR since is inaccurate if they reproduce the color, too.
The chancellor's office hero hilt was colored gold and then overlaid with a gun-metal gray to make it resemble electrum. The rib and puck parts of the hilt are colored gold, and the cone (and possibly the nipple, too, with some further color for a gradient effect) is colored in the same fashion as the main hilt. The only possible metal parts on either version of the hilt is the emitter, which may have been machined brass. This can be seen in photos of the prop(s) today with the patina that has formed over time.
The Palpy V2 (Yoda duel) is the exact same prop but for different color and an addition of a Covertec wheel at the back of hilt. The emitter is potentially machined brass, but the body "wrap" around the main grip section is a blackened brass/bronze color. The cone and puck on this hilt is a dark patina bronze, with something similar for the nipple (with some extra work for a gradient effect). The rib section remains the same gold color from the Hero but in a duller finish.
I made my own
Palpatine hilts from cast metal a year ago. They're not accurate as I wanted to add my own touches to them and wanted them more hand-made like the OT sabers. The V2 I still hold as the most beautiful thing I've ever made, but the Hero, which I tried to make in bronze to mimic electrum, turned out terrible. It's something I'd like to tackle again in future.
I'm also prepping to try my hand at making a cast-metal/machined parts Dooku, as well. I just need to finish the buck for the cast pieces.