2. Luminous characters on the back: As the name implies, this luminous character emits light from the back, so it can only be made if the character size is 8-9cm and the stroke is required to be 8-10 mm. If the stroke is too small, it is recommended to install it directly in the air, so that the luminous effect will be scattered, creating a shadow state and reflecting the three-dimensional sense of the front.