I used small LED light strings available cheaply from IKEA at the time. Each has 10 LEDs wired in parallel to a battery pack. The battery pack also has a switch and a 6.8ohm 1/4W series resistor in it.

Pulling off the plastic cover let me unsolder the wires and the resistor for reuse.

The LEDs used in the string are the type I prefer for decorative lighting because they appear like a point of light from most angles you look at them. The case is cylindrical, but the tip has a conical depression in them.

They were made relatively simply by soldering the wires to the leads, a plastic spacer between the leads, and then covered in red heat shrink. They've been quite robust despite all the pulling and tugging.

From testing, I found that the LEDs have a forward voltage of 2.0V, and with full batteries were running with 18mA each, or 180mA for the string of 10. This is why I used 6 strings and 2 resistors with the 14.5VDC supply before, as it resulted in the same current, and less wasted power than if I had kept all 6 resistors.

With the 18 strings I had in the bottle originally, it totaled 7.7W.