The M31 gallery of reverse plastic:
1959 Sony TR-86
4 1/2"H x 2 7/8"W x 1 3/8"D
Sony used reverse-painted plastic on a number of its larger transistor radios, but as far as I can tell this TR-86 is one of only two Sony shirtpockets sold in the US to use reverse-painted plastic on the dial face area. The other set was a horizontal AM/SW shirtpocket, the TR-714.
Sony TR-86 instruction guide...
Sony TR-86 box