In this talk a brief overview on light sources around the world is given, the status of the Mexican users of such facilities and of the accelerators physics in Mexico is also discussed. Then, some ideas for the storage ring of the Mexican Synchrotron Light Source (MSLS) are presented, which include third generation machines with DBA and MBA cells. Given current trends and in order to have a competitive facility when the MSLS begins operations, in approximately 10 years, the possibility of a Diffraction-Limited Storage Ring (DLSR) must also be considered. Our toy models are based on the linear lattice design, however a simpler non-linear lattice optimization is applied in order to that the dynamic aperture not be very bad.