The short answer: there is not a method out there that I would use on an airplane or car that would hold up for long. Right now the best bet is the chrome wrap and expect it to be replaced every once in a while.
The long answer:
PVD or other vapor depositions will be thin and wear. They won't stand up to the environment. It is very expensive to do large parts and the reject rate is high for large parts.
Metal filler in epoxy. This is like metal dust that can be mixed with small amounts of epoxy to make a somewhat metal part. It can be polished but won't hold a shine like real metal. It is heavy.
Chrome plating of plastic. This can be done. It generally looks good but will ware in the environment. We sometimes use this on the inside of plastic parts to control EFI and to stiffen the part. Toxic. Cracks. And not good for our use.
Chrome paint. This looks okay. It is expensive and not a great match when placed against real metal. It is hard to apply and can't be buffed. This is probably the second best alternative to real metal.
The best alternative so far is chrome film. This is used on large simi truck bumpers. When they apply this it is heated and vacuumed formed to an ABS bumper. You can simulate this process with the roll film, a squeegee and some time.
It is possible to vacuum form a thin sheet of aluminum and bond it to the substrate. But not really practical for us. They heat the metal to around 600-deg and suck it down to a material covered in thermal adhesive.
For me, it comes down to what will last. We have tried all these methods and subjected them to our environmental chamber as well as real world tests.
The chrome film would be the best for our use because it can take a few rock hits, and can be removed cleanly when the need to replace comes up.
But, there is no reason that a aluminum sheet could not be stamped into a part. Not that expensive anymore and the stamping methods have greatly improved in the last 5 years. We are stamping parts now that you would swear are CNC'ed parts.
Now, if I could have a polished RV-4 with a stamped metal instead of fiberglass and with the canopy with a 25-35-percent chrome PVD on the inside, that would look awesome and help keep me cool.