I just realised I didn't link to the reference in my last post like I intended to. So here
So I'm not going to be obsessive about a shiny metallic finish due to the amount of weathering that will be going into it.
Will rub'n'buff weaken the latex significantly? Would it affect the actual finish?
Will aluminium powder only give a dull finish? Not that it really matters, but is there something to top coat it with to give it more of a shine? Something like Liquitex Matte or Perma-wet gloss?
Is it all going to be a matter of many trials and errors?