This thing was $15, but solid glass. Would consider getting the longest one instead of the shortest one, so you have a bigger rainbow & more room to hold it without blocking the light. Real tricky to get it to work with 1 paw in the dark, but that never stopped lions before.

After much foreplay, finally got it to project white light from RGB LEDs & white light from white LEDs. The answer was the RGB LEDs really do make only 3 bands while the white LED makes a continuous spectrum even though both appear white. Most obvious is the lack of yellow & turquoise in the RGB projection.

An LCD screen isn't bright enough to project a rainbow without serious optics, but an LCD projector would reveal that all your supermodel JPEGs of the last 30 years really do contain only 3 bands of color instead of what was really there. The only way to see the full spectrum of a supermodel really is to be a politician.