I found a load of amazing designs online for adding light holders to the ender 3. I preferred not to have extra limbs standing off the printer and wanted the fewest parts to modify or add. I decided on just sticking some 12v led strips to the top brace of the printer which also served as a bit of heat dissipation.
I designed a visor that slides into the slot of the extrusion to prevent LED glare, also stops the bowden/cable snake rubbing directly on the LED's on tall prints.
I had a few XT-60 connectors i used to create a tap from the main supply without cutting wires
I had a few thermal switches that switch ON at 45C which attaches under the heated bed and makes for an automatic on and off for the light based on the bed temperature.
I printed two visors, and they fitted easily.
Rafts:
No
Supports:
No
Resolution:
.2
Infill:
20
Filament:cheap-o PLA black
Notes:
i printed on end with a large brim to add stability, also aligned them parallel to the Y axis to prevent 'swaying' with the motion of the bed.
It worked for me, you might have better luck printing flat if your bed is wide enough