I am building big castle, and I would like to put some kind of lights inside, to illuminate windows (made of trans bricks). I tried using Christmas lights, but they are too hot.
Any suggestions what would be easiest and yet the best-in-results way to put "sparkle" in castle night life?

The idea is to looks like there is someone inside and the lights are on

I would use both Lego and non Lego lights, preferring non-Lego