Thanks for the comments, friends
@ Vermin_King - the rolled paper method works well for very small diameter domes. For the larger ones, I find it better to use inside tabs.
@ Mike - thanks for the link. I should be able to find gold paint here in Portugal. Hmm, it would be risky to apply it at this stage...
Today’s pictures show a lovely detail that will be glued to the left tower. After taking the pictures, I remarked that some joints were left on the visible side. Fortunately, it was possible to rotate the parts and hide the joints.