This is a really simple project. It only takes 5 parts, about 10 minutes and costs around $2. BUT it's fun and looks really cool.
I like LEDs (who doesn't?) and have acquired all different kinds to use in projects, we are going to use one you may not have used yet - a flashing RGB LED.
"Regular" RGB LEDs have 4 legs as opposed to single color LEDs that have 2 legs. Being able to control all 3 colors independently is cool but you do need 4 wires, 3 resistors and some type of controller.
There is a much simpler version out there - flashing RGB LEDs. These LEDs only have 2 LEGS ( + and -). So how do you control the colors? You don't. There is a teeny tiny chip wired up to the LEDs inside their plastic housing that turns each LED on in varying degrees creating a color changing flashing pattern. They come in 2 flavors, fast flash and slow flash.
One characteristic of LEDs is they are usually pretty directional. What I mean by that is when you look at them from the side you see one level of brightness and color and if you look at them head on it's completely different. They sell diffused LEDs that have a frosted epoxy case/lense/housing but a ping pong ball works even better for defusing the light!
Some of the most fun I have had with these is when I put them in unusual places at night like in the grass of my front yard or bushes or under my car. People have all kinds of reactions. Of course sometimes I just turn it on at my desk and stare into the abyss.