Even after adding LED strips to my delta towers, I wanted a little more light where the printing was actually happening. So after many iterations, I finally got a combination that works for both cooling and lighting.
I used two 4020S blower fans, that are driven from a PWM variable supply. Mainly because I can do a better job of deducing where the cooling will be required and how much, better than any firmware or slicer can.
The standard axial 40mm cooling fan keeps the hot end heat sink cool itself.
Note: I only use E3D V5 hot ends. V6's are significantly smaller in height, heat sink, heater block and won't fit in my mount at all.
All parts printed 50% infill, didn't use any supports.
The LED's are from a 3014 LED strip. I cut them so each side has 6 LED's in a strip. The holes in the mount use wire left over from the 4020 blower fans. A 1.5mm hole channels the wire out and there is a slot to feed in the strip.
I use a Dupont 2x5 female end, all the red wires are for the 12V, so the LED's and the hot end cooling fan itself. Theres a photo of my wiring harness end, shown as separate wires. The grounds for the LEDS, and hot end cooling fan are spliced to a common ground wire. The RED wires for the LED's and hot end cooling fan is also spliced to a single wire and fed to the 12Vdc on the RAMPS.
For the PWM controller, the greens are spliced to a single green wire, and the two grounds for it are spliced. PWM controllers don't share a common controller output ground with the RAMPS so they have to be separate.
The two green wires are for the PWM controller to drive the blower fans to directly cool the print itself. I found not all blower fans like to be controlled via PWM controllers, in which case you'd have to add a resistor and capacitor to make a low pass filter.
The round hole in the effector is for the heater cartridge wires and the thermistor wiring. Those two items were kept separate because they, at some point, will have to be changed. I use wiring loom to keep it all neat.
All parts are mounted with M3 screws. Nylok nuts (3) are used to hold the cooling assembly to the effector. Everything else is just threaded into the PLA.