Plastic crate with smooth side walls which was semi flexible .Sand shiny services and paint with primer and yellow caliper paint .
Looks absolutely stunning. Could you share where you got the bonnet stripes from please? Which part would this be?
https://innovativepaintprotectionsolutions.com/products/mini-cooper-door-shut-paint-protection-kit-f56-f57?variant=41075288703185 Note that they indicate that these are a wear item, so may only last a couple/few years. You therefore may want to save this bookmark (as I did) to reorder if necessary, buy a couple sets, or just save the backing paper to use as a pattern to make your own in the future.