Foremost; thanks for the first hand testimonials....
Hey all. In my research I have arrived at the same "Aluminum" conclusion so far. I have an un-assembled J. Long kit and his crispy is extraordinarily thin aluminum (about US 32 gauge). I took John's sample and got on a plane in Tampa Florida (just this past May 2017) and flew to the Star Trek 50th exhibit at the EMP/MoPOP. I compared the J. Long sample to the exhibited Paul G. Allen Midgrade phaser crispy. They match. I feel like I know aluminum when I see it.
I too saw the contact cement first hand as well (at EMP/MoPOP), and it sure was old school "brown" contact cement (industrial contact cements lay-down semi clear and turn pink when they are ready for assembly. The early pink pigments turned rusty-brown over time. I worked in a cabinet ship in the 1980's).
Some OTHER remarks; I have a written request in at the MoPOP, to curatorial, asking very politely if they can put a multi-meter on the Paul Allen Midgrade crisp. If it conducts electricity it is aluminum. This is a simple non-destructive test. This could resolve what is on the Paul Allen at least. I have a similar request standing with a friend concerning another known original. I will surely share whatever response I get.
About that "white stuff". I noticed the "white stuff" too. But I noticed it first on the photograph's of the Asherman P1. The thumb-wheel was, in my opinion, definitely painted white. I have observed this in a few other un-remastered screen-shots as well, like the half-moon on the Finney P1 Hero. Both images are below. Next I thought "...why white..." then I realised that in the 1960's white paint likely looked just like the silver aluminum when filmed, especially as an accent on a black or dark grey object like a phaser. After all they were using actual 35mm film back then. White paint could have been an easy fix for those pesky aluminum crispy corners that legend says kept needing a "little trim" all the time.
Mylar™; a cool product mostly because it has a unique property, incredible tensile strength. Mylar™ had early commercial success as a use for drum heads at the start of the rock-n-roll era (ref. DuPont history dept.). No matter how hard this stuff got beaten, it was nearly impossible to leave an indentation or, put a drum stick through it. Look at a used modern drum head and you'll see my point. Mylar™ just will not emboss. Now vinyl (as is used for commercial wallcovering) is perfect for putting a pattern like this on. I bought a bunch of this alleged mylar crispy on eBay and lab tested it. It was absolutely vinyl.
Now I got a black eye already for being too picky about material specifications. Forgive this. While I was a licensed design professional I once had a vendor tell me I was so "anal" his old marine platoon could not have put a pin up my a## with a sledge hammer. I'm OK with me just the same...
As for putting a super shine on aluminum crispy's; I use a jeweler's burnishing tool. This tool is highly polished steel plated with chromium. Jewelers use it to put the ultimate shine on hand made jewelry. It out-preforms even the best Swiss Polishes (like Pollonium) and leaves no residue to clean-off.