This is my first Instructable. I didn't document it as I built it, but will do my best to photograph and explain. This project was inspired by Wire Tree Sculpture and the ever-popular Joule Thief, specifically the circuit taken from here. I've made a few Joule Thieves before, but wanted something larger and more useful.

This project uses similar methods to the wire tree sculpture for bending the wires, and it is powered by a typical Joule Thief.

Step 1: Materials and Tools

For this project I used:

Materials:
Brass wire (or a less flexible wire if you plan to attain a specific shape)
Single-strand plastic-coated wire
Old wireless router
Battery holder (AA, AAA, D, or C)
Ferrite core for winding coil
Magnet wire for winding coil
Assorted wire for making electrical connections
1k resistor
2N3904 transistor
Assortment of LEDs
Solder
Heat-shrink tubing
Plastic zip ties

Tools:
Soldering iron
Hot melt glue
Wire cutters
Multimeter or continuity tester

I chose an old wireless router as the base. This one is particularly good because it's very low and has holes in the top for the wires to pass through. It also hides the Joule Thief circuit.

Step 2: Prepare the Router and Wires

Disassemble the router and remove all internal parts. If you're unsure how to take it apart, you can probably find a guide online. The case may have hidden screws and panels that snap in.

Count, measure, and cut the brass and insulated wires for your 'tree'. Cut equal numbers of each and make sure you allow an extra 5cm for internal connections.

Pair the wires, one brass and one insulated wire together, and push them through from the top of the housing. You may also push them through separately, but I paired them because they stayed firmly in place and it made the rest of the work easier.

Join and solder all the bare wires together. I found it cleanest to join one to another in line while trimming excess wire, then bridging the last one in the row to the next row, eventually ending up at one single wire.

Strip the green wires back slightly, enough to join them in small groups. Solder each group to a piece of stranded wire (more flexible) and insulate the connection with heat-shrink tubing.

Step 3: Prepare the Power Source

Rather than cover this in depth again, you can make reference to the hundreds of good howto's for making this circuit. Again, I used this one and have been very happy with it. You could always get creative and instead of the JT circuit add a small microcontroller or Arduino to make it interesting.

Test the circuit before final assembly; connect the jewel thief to the wires, using the bare wire for negative and the covered wires for positive. Temporarily connect one LED to a bare and insulated wire from the top side, then manipulate the wires from the bottom side to test that it remains on and nothing shorts out. It's easier to find and fix now.

Step 4: Finishing the Internal Connections

Fix the JT in place using whatever means you prefer. I used hot glue to keep it and the wires in place.

Shorten any long wires and make final soldering connections.

Attach the battery holder to the top of the unit using hot glue.

Run the battery wires through the top of the unit and solder to the battery holder.

TEST AGAIN!

Reassemble the body of the router so it rests nicely upright.

Step 5: Untangle the Wires and Form the 'tree'

Since my design had a long straight 'trunk' and I used very flexible wires, it was necessary to bundle the wires together before they diverged or the design would simply fall over. I also twisted the wires as a group from the base up.

At this point you need to decide how you will shape the tree and bundle it if needed. If you have very flexible wire like I did, you may want to separate the wires into several bundles temporarily to keep them orderly. The Wire Tree Sculpture page has very good instructions on how to style the tree and get the appearance you want.

Remember: As you separate the wires into groups you must have equal numbers of bare and insulated wires in each, eventually resulting in a twisted pair at the end of each branch.

Step 6: Add LED Lights

The last step is to add your remaining LEDs. I worked with the battery installed so I would know immediately if each connection was made correctly. The brass wire was difficult to solder to, but it worked best if I heated it well and tinned the end with solder first.

Remember to put the heat shrink tubing on the wire before you solder. It's an easy mistake to make.

Step 7: Final Thoughts

You may notice that not every branch has an LED. The only reason is because I ran out of small LEDs, so I distributed what I had around it and used a mix of green and yellow. I've found that it makes a dim but pleasant light which is perfect for lighting my bedside table at night without disturbing my sleep.

Suggested improvements:

-More efficient JT to get brighter light - I used a large toroid and ordinary insulated wire to wind the toroid coil for this JT. Compared to other smaller designs it seems to have low output. My other builds all used magnet wire and small cores, with better results.

-Multiple JTs to get more light output

-Abandon the JT and use normal battery power plus a microcontroller to get special lighting effects

-A photosensor to turn it off automatically in daylight

Your comments and suggestions are welcome. Thanks for reading!