It would be an interesting process, I imagine the aluminiuim must be sprayed on if it's .6mm thick.
Trouble is most current windsurfing boards have a double carbon sandwich (not just a foam blank with a single outer layer like this).
Aluminium is a great material but I agree with Moose, I don't think .6 of a mm would even be close to a double carbon sandwich in terms of flexural strength and crack resistance.
I imagine it would dent very easily at .6mm. I can't quite work out how you would get a good seal around the deck fittings and finbox etc. It would corrode, and it might be a bit tricky to repair.
Apart from that it's a great idea for anyone who wants to look like a giant fishing lure...

PS where's my cat gone?