Iif you open up a Corgi Batmobile, you can see how that the original "rivet heads" are actually part of the same single piece of metal as the upper body half.
never used rivet for assembly the lower body with the upper body moulding,
Corgi used a specific tools for dump 4 points of the lower body, and for
dump 2 points from inside main part.
For the 4 points of the lower body, it’s paint in black when the lower body was paint, but when the tools dump it, the black paint goes on. So the 6 paint look like same silver color, without paint.