Pulsating LED?

I am looking for a solution I can buy to get a pulsating LED like the ApplePpowerbook sleep mode’s blink. I want to put it in a model and have it look like the red eye in Dave from 2001 Space Odyssey. Any advice? I know nothing about electronics. Hoping for a solution that can be battery powered and can be bought off the shelf.

I think this is exactly what you want:

This is cool, but requires AC power:

Mathmos makes a bunch of battery-powered ones: