items():
            frac_mass, density = self.materials[name]
            mat = self.create_material(name=name,
                                       fractional_masses=frac_mass,
                                       density=density,
                                       thickness=thickness)
            res[name] = mat

        return res
    @classmethod
    def get_stix_ebins_transmission(cls, ebins=ins.ebins):
        pass
    @classmethod
    def create_material(cls,
                        name=Non