We have recently demonstrated various quasi-2D disclination networks in blue phases confined to thin layers, ranging from rings, skyrmions, to double helices, which can provide arrays of trapping sites for an easy assembling of colloidal particles in complex 2D lattice structures. In this brief review, we summarize main findings of our phenomenological modeling combined with topology. Effects of confinement, particle sizes and anchoring are discussed. Quasi-2D colloidal crystals can be easily manipulated by external stimuli via affecting liquid crystal or colloidal particles and offer means for novel applications in photonics.