For years my ornaments sat on the tree unlit. This year I decided was the year to fix that. My solution a 8.5v AC regulated power brick (12v shown in video) connected to a 1 to 8 splitter used to wire up CCTV cameras. For the test I used the screw wire connectors but for the tree I am going to use regular 2.1mm pigtails. I have tried 3, 5, 7 and 12 volt transformers in AC and DC the AC ones seem to work the best. (the DC ones do not light the ships evenly).
The 8 way adapters were $4 on ebay the pigtails to connect run 50 for $20. You will need some black 2 conductor wire to extend the length and you will need at least one old Christmas light set to cut up so that you can get the female connectors off it. In the video I used a 12v brick. It was too strong and melted the runabout. I stepped down to a 9v for safety. It does not light them up as bright but still works.