Moon lamps are usually made up of PLA (plastic) material. Even though this material is not strong, it is preferred because it can be printed on a 3D printer. To make a lamp that is perfectly spherical and closed from all sides, 3D printing is the fastest and most convenient method. Although, you might come across some premium options that are made up of ceramic or even glass material. While these options are more expensive, they are even more fragile and need more care.