A method of manufacturing an ink cartridge system includes the steps of using a first mold to make a first case member a first ink cartridge, using a second mold to make a second case member of the first ink cartridge, using the first mold to make a first case member of a second ink cartridge, using a third mold to make a second case member of the second ink cartridge, using a fourth mold to make a first case member of a third ink cartridge, and using the third mold to make the second case member of the third ink cartridge. Moreover, a size of the first ink cartridge is not equal to a size of the second ink cartridge, the size of the first ink cartridge is not equal to a size of the third ink cartridge, and the size of the second ink cartridge is not equal to the size of the third ink cartridge.