This project is from the collection at http://www.bigclive.com
Step 1: Getting the bits together.
You'll also need some miniature sockets for the LEDs. I used standard Molex style sockets with a 0.1" (2.54mm) pitch. These are actually designed for interconnecting PCBs, but they also make great LED sockets. They are supplied as a plastic shell and individual contacts that click into place once you've attached the wire.
You'll need some resistors that will depend on the voltage you are going to use the display at. Typically 330 ohms for up to 9 volts and 1000 ohms for up to 18 volts. Normal quarter watt carbon film resistors are ideal.
Some heatshrink sleeving is good for covering the resistors with. It makes them look neat and keeps them from shorting against each other. Choose a sleeve that will slide easily over your resistors. Typically about 3mm (about 1/8th of an inch) inside diameter.
LEDs. Any type shape and size as long as the leads are on 0.1" / 2.54mm spacing. Diffused LEDs will give bright dots of light on the ornament while clear LEDs will project random splashes of colour around the room. Choose the brightest LEDs you can find. Ebay is a good resource. Don't worry if you get some cheap LEDs that fail, 'cos you can just plug in a new one in seconds!
Finally choose a suitable power supply. This could be a battery pack or a plug-in mains adapter. The adapter doesn't need to be regulated, so you could use a general purpose one. You could even run the effect from a solar power supply like the ones used for outdoor solar garden lighting.