Today, I tried my cheap little RGB LED nightlight with the red LED covered, and doing that would essentially make it a MV style night light, which I eventually hope to make into a bucket light nightlight.
The LEDs are just red, green, and blue 5mm straw hat LED lights.
What should I consider if I decide to make a LED night light that looks like a clear MV?

If you look at the MV spectrum, you see a yellow, green and blue. So these three LED colors will be what I would start with. Then tune the relative intensities...

A clear MV normally looks white by itself, only the illuminated things have a bit greenish tint...

I think that sleeping with a bluish light is less healthy than with a warm light.

http://lamptech.co.uk/Spec Sheets/D MB Iwasaki MB2000.htm

Note the Violet and 2nd Green bands, they have quite a bit of power in them which take away from the power of the 1st Green and Blue



In most nightlight the LEDs are in series on a capacitor based current limiter sort of circuit, sometimes with a Zener diode, rectifier bridge or smoothing capacitor

To change the LEDs relative brightness add resistors parallel to the LEDs that you want to dim down

The total series voltage will still be the sum voltage of all LEDs, so if there is a Zener or smoothing capacitor their voltage ratings might have to be upped if you change from 3 to 4 LEDs for example. And if there is no full rectifier bridge, make sure there is a path for the reverse AC polarity to discharge the capacitor

Properly mimicking a MV spectrum would be hard to do because of all of the different frequencies.

There are only 4 visible ones in 4 peaks (well also some Incandescent light from the electrodes, but that is insignificant), so it would take 4 LEDs (or 4 types of LEDs anyway). Then its up to you to get the power of each correctly