northern lights

This is a very interesting idea!  Wow!

I can think of several approaches you could experiment with.  The first might be pricey for you - not sure what you mean by too pricey.  Anyway, the Philips Hue lightbulb changes colors and hue and can be programmed with Apple and maybe other apps, etc.  I'm sure with a bit of experimenting with shades to block colors in some direction, maybe prisms, etc., you could get a type of changing color northern lights effect.  

Requiring more home-made stuff but probably cheaper:  you could just get several colored lights - red, green, bluish and shine them up at a wall, up and through through a transparent trough filled with a bit of water, then use some sort of mechanism to shake to water and/or make it wave back and forth by rocking the trough so that it would work as a variable lens to distort the light passing through it.  Rather Rube Goldberg I admit, but I thinkit could be made to work.

I had to go sit on the couch, and about dropped my coffee, I just got tickled, at your comment, which has been true for the last few days !!!

Now we have 2 projects, directing a light show, and trying to buy the vacuum

cleaner , even though we have 5 in the house, 

Little bit on the serious side,  Amazon had the LED light strands on sale, and mounted under layout-- I havent gotten a mirror yet, but the shadows , ( bought orange for sunset) are unique,    -- think about some LED's from EVANS DESIGNS,

and cut into your walls, and mount opaluscent (sp), style , glass , if you dont mind the sheetrock work,  !

I have seen small- to medium-size fiber optic Christmas trees that change colors. Just food for thought. 

If you have a Spencer Gifts store in your area, check it out. They have odd-ball light projecting stuff that may work for you.  www.spencersonline.com

Maybe their rotating 12" disco ball?

The few responses I have received really run the gamut.  They are all very interesting and gives me a basis to start doing research.  I appreciate the time and effort of those who responded.

Bob

I would think the key is to diffuse the light source with smoke or tissue paper. Something to make the colors softer and flow together.

This is the professional answer, although a target surface is required. Find a way to get this effect. X-24 Aurora Borealis  Roscoe X-24

Projector with wheel diffusion.

Focused LED bulbs tend to provide a projected beam. Connected to a controller of some type.

Perhaps hiding the light source inside of a mountain with some type clear or tinted vinyl screen attached to the mountain. Screen could be shaped in a wavy fashion.

May also have room light or daylight issues.

We would all like to see it, if you create it.