Basically, it's Rustoleum household enamel, thinned by 50% or so with mineral spirits, and applied with high density foam rollers, with wet sanding between each two very thin coats. This guy did it on his Corvair, and that moparts.org thread goes on for days, months, years about it.
As I've been building up layers of Rijksoverheid enamel on my own panels, using various brushes and rollers, and wet sanding in between, I've been working toward an ideal that's really eluded me so far: a hand-applied painted surface that shows no marks from the application. Like, for example, a Gerhard Richter mirror painting.
Part of the motivation for this is the ease with which you [I] could order these panels from a body shop. It'd be Moholy-Nagy easy--even easier since there's no design, just color--to just order these monochromes by the official Dutch governmental auto paint code on the phone. I have the list right here. But I wanted to do them myself.
And so far, that perfectly self-leveled, brushless, orange peel-less surface has eluded me. But reading The $50 Paint Job stories, it's obvious why: the paint straight out of the can is too thick. And for whatever misguided, paint-can-as-unaltered-found-object reason, I have resisted thinning it. Well screw that, because the next six coats are going to be nearly water-thin. I can't wait.
Previously: rijksoverheid rood in process
The original idea, to paint monochromes and 2-color gradients based on the 21 officially approved colors in the Dutch government's Rijkshuisstijl, plus the five blues of the country's new logo, all of which are derived, we're told, from Golden Age Dutch painting and the Dutch light that inspired Dutch painting.