Easiest way to get 36 -12V sources?
simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. Modified schematic.


  The problem becomes how to get those 36 12V supplies, without increased load on one LED reducing the power available for the others.


Figure 1 shows the normal method of achieving your goal. A common 12 V supply is used for all the (12 V) LED lamps. M1 - M8 provide a switchable return path to the power supply. Provided V1 is stabilised and has enough current capacity then there will be no interaction between the LEDs.