The slides of the talk Nonlocal multicomponent metamaterials I gave at the MexSIAM Annual Meeting 2021 on June 23, 2021 can be found here. Using a spinor-like representation, I can extend the calculation of the macroscopic response of a metamaterial to multicomponent systems with and without retardation. The trick is to use an Euclidean instead of a Hermitian inner product to define matrix elements, and to use a spinor like representation of the fields, with two components +k and -k, corresponding to Bloch waves moving in opposite directions. This way, all relevant operators become symmetric, even when there is dissipation, and I can use some of the usual linear algebra theorems about orthogonality to build a Haydock representation that allows an efficient calculation of the macroscopic response and the microscopic fields. Some tests are shown to verify that the formalism works. The ideas were published here. They have been implemented in the Photonic package (link1 and link2).