Found this model of a star decoration on Thingiverse.

Did a quick print run and instead of using a string of LED lights just grabbed a handful from the drawer and a small buck converter.

The converter is set for 3v output (nominal forward voltage for the LEDs) and the LEDs are in parallel. 12 LEDs and it's drawing about 200mA - so that's about 16mA per LED as well as a few for the converter itself.

I could have used resistors but the current draw was a little high for the ¼ watt ones I have (especially if any of the LEDs fail with a short) - and I didn't want to have to make a large cluster of resistors to get the right dissipation/resistance.

The USB cable was an old 30pin apple USB cable - which we don't use any more and which had frayed near to the 30pin connector so I could just chop that end off :)

The result: