Tamiya Acrylic Orange X-26. About $2 a bottle (one bottle is a lifetime supply) at any hobby shop. It's been written up many times on OGR. Here's the effect on a 3mm through-hole and a surface-mount white LED. It adheres well to the plastic lenses on an LED. You have to experiment with how much tint you want - multiple coats can be applied to darken. It thins or comes clean with rubbing alcohol if you've gone too far.
