As I understand it, you sanded/polished the edge of the first BMF piece before you set another one up against it, and then you parallel-sanded the boundary line between the two pieces. Do I have that right?
I've been mostly using Alclad II, but sometimes it has little nits on the surface, and some areas turn out dull, even if there's a smooth coat of Alclad Black Lacquer underneath it.
I haven't figured out why those things happen, but BMF doesn't have those problems. That's why I tried using it on a set of Baby Moon hubcaps - they need to be really smooth. But with BMF, I kept getting wrinkles on the perimeter. Your method looks great if there's a short boundary in a hard-to-see location, but you can see how it wouldn't work for smooth hubcaps.
So for this job Alclad was the only way to go. I had some extra caps and I managed to get four good ones with Alclad, so I'm happy for the time being. But I'm going to order some Spaz Stix and see if I get a more consistent smooth gloss.
Does anyone know whether Alclad's black undercoat will work with Spaz Stix?