How to make the light source of light box more uniform

You can't use spray-painted cloth for such a small size as 30X40. You can make this material with light boxes at a very cheap price. The light box is light-transmitting. You can use a light guide plate with such a small size and a common ink light guide plate, and put LED hard light bars on two sides of the light guide plate. The effect is very good, the brightness is very uniform, and the power consumption is very small. You can buy light bars at Taobao or your local advertising material store. You can use the 3258 model or ordinary straw hat to hard the light bar, so that your DIY effect will be good and the grade will not be low.