Those push on covers for CSK Pozi screws as found on some kitchen cabinets, etc. The smaller of the two commonly available, so about 12mm diameter. Loads on Ebay, but not the colour I need - dark grey. It's for the old car - has had the windscreen replaced and they lost some of the originals from the screen surround trim.
I know they could be painted at a pinch, but not had 100% success with this before, even using a primer and paint sold as being suitable.