Recently, we showed that natural linear defects are the origin of the high critical currents in laser ablated YBa 2 Cu 3 O 7-δ films. Combining wet-chemical etching and Atomic Force Microscopy, we find that these dislocations are created by island coalescence during growth. Consequently, the defect density can be reproducibly varied by manipulating the density of growth islands, which in turn depends on the substrate temperature. Interestingly, the radial defect distribution function approaches zero at small distances, indicating short range order. Therefore, we are now able to study vortex matter in films with a tailored non-random distribution of natural strong pinning sites.