WOWOWOWOWOW!!!! After spending some time at work, I've finally read Your posts... And I find that You are doing great with old owen!!!
GREAT WORK WITH THIS POWDERCOATING!!!!
I've spent some time in my local library and I've found domestic machines used to make Your parts covered with gold, Zn, Cu or any other metal that is normally used to cover metal pieces :-)
So guys, I've got idea of home made sandblaster, Tim has his domestic powder coater

Let's do galvanizing machine... Anyone interested? I can fabricate how to do instructions...
Ose - You would be able to yellowcoat any part You want just at home... Or just galvanically change the color of any alluminnium part You like

/Bike parts are often colored like this/
Well, I'm still impressed by the level of restoring old cars You present here... BTW E30 is the oldmobile.