What is the difference between of 2d and 3d keychain?

The biggest difference between 2D and 3D effect on Metal Keychain is that 2D design is with flat metal lines, but the metal line on 3D design is with curved surface, whn you viewing the metal key ring from side will makes this easier to understand.

Custom Keychain made with 2D design can work with all colored enamel filling processes, but due to the production limitation, it is only able to fill soft enamel or hard enamel color without grinding if making with 3D effect.