Assembling complex architectures with novel geometries and tailored properties requires the development of suitably designed colloidal building blocks that assemble through specific and directional interactions. Magnetic colloids have the potential to provide the necessary tools to obtain programmable building blocks due to the innate directionality of magnetic interactions. Magnetic dipoles can be permanently embedded into particles and they allow for remote control and manipulation via external fields independently of the chemical and physical composition of their dispersion medium. These properties put magnetic colloids at an advantage point over other currently available systems. In this chapter, we discuss recent advances on the synthesis of magnetic model colloids and their role in the preparation of rational structures via self-assembly.