I have a friend who owns a Stage sound and lighting company (I work for him sometimes).
Recently, they have been using LED stage lights for the smaller venues. These look like a normal stage light but have an array of red, green and blue LEDs instead of a bulb.
Whilst the light output cannot match a traditional type with a 500 watt bulb, the light output is quite impressive.
He had a couple with a row of green LEDs not working, so when he got replacements, he gave me the the PCBs to play with. In each case it was just one LED not working so I repaired one with an LED from the other to give back to him as a spare.
The remaining one I will use for a 5x4 light source. The LEDs occupy a 6" diameter area so I can re configure it just for the 5x4" area.
These lights are very cheap now, so could easily be modified for enlarger use.
I am planning a variable mix (PWM) between blue and green with an all on full option for focusing.
Each colour draws about 300mA at 30 volts so there are no horrendous power supply issues.
(please excuse the crappy pictures. I just put it on the scanner).