x1 is cloisonné ornamentation on x2 that exhibits cloisons/cloisters/compartments/cells/separated box regions (filled with/meant for) x2 and with separating barriers x3 (usually metal).
The existence of actual raised barriers is important. These are not just disparate and distinct regions touching one another and transitioning sharply across the interface (this would be the case murals, brickwork, art made from magnetic phase domains, etc.). The wall is an emphasized part of the decoration; in fact, it is thick and the compartments/cloison do not touch eachother. An additional layer of metal may be laid over top for added ornamentation.