Korean DIY site Hobby:Design has a neat idea for a light bulb that doesn’t need electricity or electronics to work. The not so secret ingredient is of course glow in the dark pigment. Leave it exposed to bright light during the day and you get soft lighting at night. You can’t turn it off though.
Hobby:Design made the luminous bulbs by first making a cast using an actual light bulb. Then they mixed silicone with luminous pigment and poured the resulting mixture into the cast to get a bulb-shaped replica that glows in the dark. To complete the simile and make it easier to hang the bulb, they screwed the replicas into bulb sockets.