The parts are fairly cheap and the project is fairly easy. You will need to strip wires, solder leds, and be able to use a power drill. With LEDs cheap and long-lasting this project will add a warm glow to your house.
Once you have purchased the parts you need (You likely have most of them already) actually putting the bar together should take about 3 hours (if you are inexperienced).
This instructable is designed to teach with pictures as well as words. Most of the pictures have notes added to them with tips and information.
*** I am not liable for any injury, property damage, or any other losses that happen within this project. You will be working with electricity and should be careful. Though the voltage and amperages I used in this project are not harmful (or even be felt), using a more powerful electricity source, and the use of hot objects (Soldering Iron & Hot Glue Gun) can cause damage. ***
Step 1: Parts & Tools
Most of these parts were purchased at The Home Depot and Lowes.
Metal Wire Cover (Light Bar) $5.00 for (1) 5' bar. Used to keep people from tripping over wires in the home or office, I modified it to become my light bar. You could also use wood, PVC pipe, or another material. (Though I suggest something compact and tidy).
Rubber Insulated Clamps (3) $1.25 for 2 - These are used to mount the light bar to a surface.
Electrical Tape (1) $4.00 for 66' - Used to hold pieces together and insulate wires from bar.
Wet Rag - Any cloth or sponge will do, just soak it in water, its used to clean leftover solder off your soldering iron.
LEDs (18 for one light bar) $10 for 100- Pick whatever colors you want. I also suggest fading LEDS. You can use any voltage you want, though most colors fall in two categories, 1.9-2.1v(red, orange,yellow), and 3.0-3.4v (green,blue,white). Brightness is up to you, 10000mcd-18000mcd (Millicandelas) are plenty for night lighting, something like 25,000mcd may be too bright for night time, but good for accent lighting (glowing under furnitur, though 35,000mcd or higher can even be daytime lighting. Real life stores are far too expensive, so on EBay you can get them from Hong Kong for 1/20th the price. I suggest the sellers HKJE LED or LED-HK
Hot Glue Gun $5 - Get a lot of glue sticks, as they will hold things in place and insulate.
Power Supply (1) $1- Any source of power will do, though LEDs run on DC. Your voltage can be whatever you want, but you must choose your own resistors. (Supply Voltage should be higher than the LEDs Forward Voltage, around 300mA for one light bar (Milliamps are the max amount of LEDs you can have). I got three supplies for $3 at my local GoodWill charity.
Resistors (At Least 10) $3 for 100 on EBay, I suggest ResistorsPlus- These keep the LED from taking in too much electricity. It can change a 9 volt or 12 volt power supply into a 3.3 volt for an LED. For my 9 volt supply, I needed 150 Ohm resistors (9 Volts for 2 LEDs in Series). Calculate yours @ ledcalc.com A common rating is wattage, this simply means heat dissipation, you can always have the W number higher than recommended, but never lower. A higher wattage rating costs a tiny bit more, and is larger, for the most part 1/2 watt is fine, unless you begin using ultra-high power LEDs (like Luxeon Stars which can need 3-10W resistors).
20 Gauge Speaker Wire (Around 8-10 feet) - Used to connect the LEDs to the power supply.
Soldering Iron $10 (1) - Cheap, everyone should have one around. A 15 Watt iron from Radioshack works fine.
Solder (1) $3 at Radioshack- Solder with flux. I recommend silver solder at 0.022" thickness and a rosin core, it's easier to flow and more durable. Used to connect LEDs to the Speaker Wire.
Needle-nose Pliers - Used to bend LED legs.
Insulated Quick Disconnects (Optional) $2 for 12- This is used to easily plug the power supply into the light bar. You could just solder the power supply wires straight to the speaker wire, but then you always have the cord attached. (***Update, I now recommend using 2.5mm DC barrel plug connectors, they are much more durable, easier to plug in, and make a stronger connection. Buying them online is semi-random, try eBay as always**
Power Drill (1) - If you don't have one, ask a friend.
13/64" Drill Bit (2) - $1.50 for one. Used to drill the holes in the light bar. 13/64th" is the perfect size for a 5mm LED, it keeps them from going through the hole and holds them in place.
Wire Clippers - Used to cut the legs of LEDs. You can use some small scissors as well.
Awl - Something sharp with a fine point. I'm sure you can find something.
Scissors - Used to cut speaker wire and electrical tape.
Wire Stripper or Knife - Used to strip plastic insulation from the speaker wire.
If you are new to LEDs or soldering, I suggest viewing this guide @ llamma.com