FWIW - This probably won’t apply to the LED’s and lights being used etc but there are some lightsources bright enough shine through a couple of layers of black paint.
I learned this the hardway lighting a Star Trek The Motion Picture- USS Enterprise back in 1979-1980. Luckily, I tested the saucer in a dark room before gluing it together. Had to line the insides of the model with aluminum foil to get the model light tight.