Since the breakthrough discovery that micro-structured composites can possess exotic electromagnetic properties, these professed meta-materials have been proposed for use in a host of extraordinary devices. To be effective, the material properties must be specially tailored, the corresponding micro-structure intricately designed. Such is often a tortuous task, owing to the arguably unintuitive mechanisms which map topology to performance. It is in response to this challenge that this thesis was undertaken. Herein a number of novel design concepts are proposed; coupled with optimization algorithms borrowed from several research fields, the efficacy and practicality of metamaterial composites are enhanced.