When you want to go an easy way or want to build your overhead on the lowest budget as possible, then you should just print these on a normal sticker sheet. But I have choosen a little bit more exciting way.
I think these stickers on the Boeing 737-800 overhead are more thin plates than real stickers and so I searched for a material that comes near of this. I found a 1 mm thin white polyurethan sheet. This sheet, sprayed black and engraved on my laser, looked exactly like the plates on my reference pictures.
The download contains the dxf-file that you can use to cut out and engrave your own plates on your laser or cnc.