Optogenetics enables light to be used to control the activity of genetically targeted cells in the living brain. Optical fibres can be used to deliver light to deep targets, and light-emitting diodes (LEDs) can be spatially arranged to enable patterned light delivery. In combination, arrays of LED-coupled optical fibres can enable patterned light delivery to deep targets in the brain. Here the authors describe the process flow for making LED arrays and LED-coupled optical fibre arrays, explaining key optical, electrical, thermal and mechanical design principles to enable the manufacturing, assembly and testing of such multi-site targetable optical devices. They also explore accessory strategies such as surgical automation approaches as well as innovations to enable low-noise concurrent electrophysiology.