Might sound silly but cut the bottom off a coke aluminium can and see if it will fit.
Darryl with the burgandy GTS (Works at wanneroo auto parts) has done it and it looks great. Wouldn't have picked it if he hadn't told me.
Had a nice aluminium finish with a Nissan sticker on it.
It depends on the size of your wheel flange plus you'll have to make 4 of them.
Cheers