Note the tailpiece and headstock overlay, both typical of late 1930's National ukuleles. By now no large body ukes were being made, and, it seems, few small bodies either.
At this time there was a passion in the USA for 'wood graining' metal items, everything from refrigerators to National and Dobro's steel bodied instruments were painted like this. The paint was probably Dulux from Du Pont. It adhered better than the Duco used on earlier instruments, (although this example is somewhat worn) and was glossier in it's finish.