Choose a semi-transparent filament. I'm using PETG Clear Glass from MakerGeeks.Print the main ornament as a shell (ie, 0% fill, 0% top/bottom). Use a large layer height. I'm using 0.36mm with a 0.4mm nozzle with a shell thickness of 1.2mm. A slow speed of 20mm/s works great for this material.Print a threaded insert. Glue this into the ornament opening. I find CA (super glue) works well. I printed these at 100% fill and 10mm/s, to create high quality threads.Decide if you want to be battery powered or plug in to the wall or computer. Either one prints similarly to the threaded insert.For battery powered, you can expect the batteries to last 24-36 hours before some colors start dropping out. I highly recommend silver oxide batteries for this, as they have slightly higher voltage and a much better discharge profile than alkalines. To assemble the battery cap, insert the cathode (the shorter lead) into the bottom hole and carefully bend the anode around the chamber. It should fit into the channels provided. I find a little give and take between inserting the cathode and measuring and bending each joint of the anode works pretty well. The last step for the anode is to bend a joint to fit into the hole on side. It should stick into the chamber and provide a contact for the + end of the top battery. With the anode done the cathode, which is already through the bottom hole can be curled into a spring connection for the - "button" end of the bottom battery. You should trim 1/2" or so off this lead, depending on how tight you make the spring terminal. Now insert both batteries, button sides down, facing the LED. They should fit snug and secure. If you need to remove them use the punch out hole on the side. Thread the thin wire through the inset loop on the top of the cap and form a loop to attach your hook. If your wire doesn't go around the loop in the cap you can safely glue both ends of the wire into the holes instead.If you are going to make a plug in ornament, first wire the hook on the top. Insert both ends of thin wire from the top, forming a small loop. Twist the wire ends together inside the hollow cap. The hook can be threaded through the loop on top.Now locate a spare usb cable, ideally thin like for an ipod. Snip the end off (I did mention spare cable, right?). Feed it through the side hole of the cap. Push the twisted hook wire out of the way if needed. Pull enough usb cable through the hole to work with. Cut the outer sleave and inner braided shields back a couple of inches and snip the green and white wire off while you're at it. The red and black wires are all we need. Solder the black wire (-) to the resistor and the resistor to the cathode (shorter) LED lead. Solder the red wire (+) to the anode LED lead. Use a little electrical tape, heat-shrink tubing or other material to avoid shorts. Pull the assembly back into the cap as far as possible. A little hot glue into the cap now will hold things nicely in place. Thread the cap into the ornament and plug the cable in.Here's a video showing the colors changing: https://youtu.be/_QmUB1bF-fc