I was able to leave the light on for about 6 hours straight without changing the 2 9V batteries. A word of caution, this costume is meant to be worn at night, the light is faint when seen in the daylight, see the 2nd pic what happens when a flash is used. I used 3 LEDs and stuck to the typical 350mA current specified by the manufacturer. Adding more current will simply burn them out faster so don't do that =)
Step 1: Materials
3-4 High Powered 1 Watt Green LED's - you can't use normal LED's, they simply aren't bright enough. The ones I purchased were: Luxeon Star LXHL-MM1D. Typically rated at 3.42 forward voltage and 350mA. I think their lumen rating is about 25 lm +/- 10%. A different datasheet (for the same product, weird right?) rated them at 50 lm. I don't have a tester, but I'll stick with the lower figure.
3021 BuckPuck - Purchase the one that fits the mA rating of your LEDs to save costs buying resistors. The buckpuck regulates the current to the LEDs, it provides a constant source of current regardless of the size/voltage of your battery pack.
-- You might be able to get away with a PowerPuck, a smaller version of the buckpuck, but the max input voltage is 8v. Only good enough for 2 LEDs...
Both can be found either at: Future Electronics (cheaper prices and more selection/product info, but slow shipping) or The LED Light (prices are slightly higher, but shipping was FAST [2day from NV to CA]).
Resistors - depends on which buckpuck you buy
Wire - to solder the LEDs together, and a longer length to run from the light, down the pole, and into your battery pack. This depends on your height!! I used around 24ga
Altoids Tin - To house everything
Electrical Tape or shrink wrap
RadioShack PCB (optional)
SPDT or SPST Switch - Rated at least the voltage of your battery pack
(2) 9V Battery clips - this also depends on the eventual battery pack
Thermal Paste - Helps in cooling. These suckers NEED this
Large Binder Clip - my ghetto heatsink
Smaller Binder Clip - my way of securing the light to the structure
GE Silicone - To waterproof the light
Optics for LEDs - Usually you'd purchase lens holders and lenses for the LEDs but since I wanted the light to be dispersed and not focused, I just left them naked. The viewing angle of the LEDs is 110°
3/16" Wood Dowels - or something lightweight and sturdy and cheap! These were 12" long in packs of 20 at my local craft store. Again, depends on your plans
Hot Glue & Gun - to assemble/hold the sticks together
I spent a lot of time on this. I ended up using the white parts of plastic bags and just fused them together. Cloth proved to be too grainy, not waterproof (in case it was a rainy Halloween), and a little heavier.
You'll need to find something to "wear" the plumbbob. It needs to be lightweight, and substantially sturdy. I tried using wire hanger, but it was too flimsy to hold the plumbbob at a sufficient height. I used a rod from window blinds (the one that opens/closes the slats)
Step 2: Building the Light
The calculation is: %IOut = R1/50.
If you Solve for R1 at 100% Output, you'll get 5000. This means a 5000 ohm resistor will output 100% current (1000mA). This is crucial to why in the materials section I said to choose the buckpuck closest to the rated mA of your LEDs. If you're going to reuse the buckpuck for a different project down the road, then by all means, buy the 1000mA version and just toss in some resistors.
I've done some simple calcs for resistor values (in ohms) based on an 1000mA buckpuck:
Connect 2 9v battery holders together in series by stripping and soldering a black wire on one to the red wire on the other. Solder these together and wrap with electrical tape. This gives us 18V. The LED's have a forward voltage of 3.42v each. Total voltage required in the circuit is 10.26v + the 2-3 v required for the buckpuck to operate. 9v batteries are small and compact, and fit perfectly within an Altoids tin.
The red wire from the battery pack should go to the Vin + on the buckpuck, and black wire from the battery holder goes to the Vin -
Solder the resistor (optional) between the REF and CTRL pins
Solder the 3 LED's in series... in short:
Solder a wire from the LED+ pin to the + of one LED. Then solder the - pad on the same led to the + on another star. Repeat. You should have the final LEDs - pad connected to the LED- pin of the buckpuck
Fire up the light!
Step 3: Making the Light Holder
1) heat! these things can get hot! you'll need a heatsink to preserve their long-life characteristics
2) breaking! People get rowdy and things happen, you wouldn't want your hard work/money go to waste right? if a solder pad breaks off, you're kinda screwed (however there are 2 of each polarity on the star)
I found that a large metal binder clip is shaped like a triangle, which is perfect for distributing light in a hexagonal shape! I attached each of the LEDs to one side of the clip and removed the silver metal legs.
I then fed the power wires (from LED + and -) through the holes where the metal legs would normally go. After applying a little bit of thermal paste to each LED, I put GE Silicone on each one to hold them down. Don't use hot glue here, I'm pretty sure it would melt.
If you're having trouble keeping things in place, tape down 2 LEDs with electrical tape while you put silicone on the other one. It takes about 4 hours to cure so be patient!
Step 4: The Structure
Basically, following the PDF below, cut the wood dowels or your choice of material to size.
Each base side of the hexagon is 3.75"
The length from the verticies of the hexagon to the point of the structure is 7"
Place the pieces for the initial hexagon and hot glue the ends together.
I find that the easiest way is to print the PDF actual size on 8.5" x 11" and just use it as a guide.
Put a wooden dowel between the posts at the top of the structure to try to evenly get them spaced together. Hot glue cools really fast so you'll need to be quick, but it also comes off wood and paper really easily, so there's an advantage for you.
This "center" dowel can be any length, but I made is slightly longer than the height from the base to the point. My plan was to put the dowel in the empty space of the light holder, and then to secure it on with the smaller binder clip. I don't have pictures of this, but I'll do so if anyone is confused! It really depends on how you plan on securing the light and the pole to the structure.
When you make the bottom of the structure, in place of the dowel connecting the points together, use something hollow, like the tube of a BIC pen. You'll need the diameter to be big enough for you to 1) slip the LED power wires through and 2) give you a way to secure the structure to the pole, (ie a straightened wire hanger on a stick)
You can clean up the blobs of hot glue with an Xacto knife.
Follow the last picture to get an idea how I secured the light to the structure. Basically the center dowel on the top part of the structure fits inside the triangular hole of the big binder clip. Then the smaller binder clip was clipped to the dowel and hot glued with the silver legs in place. After the smaller clip is hot glued, slide the big clip down so the small clip fits inside of it. It should be snug as long as the metal clips on the small clip are still there!
Feed your power wires down through the hole in the bottom structure
Glue the structure together. Or Don't, you can glue it together later after you've applied the covering material.
Step 5: Making the Material
I cut the handles off of 2 Target bags, and pretty much tried to leave myself as much of the white opaque plastic as possible. I fused them together by following this etsy post on how to fuse plastic bags. Instead of parchment paper, I just used white printer paper.
Follow the picture:
Print the PDF > Create the material "wrap" shape > trace this onto your material and leave yourself 1/4-1/2" room > Cut the material > Wrap it to the structure, fit and glue.
When I made the PDF, I accounted for longer bases, but you should def leave yourself more room on the material because it's easier to cut excess off rather than trying to patch a hole...
Step 6: Attach the Pole!
In the light, the brightness isn't that great, esp when someone takes a pic with the flash on. This can be attributed to me using the 1000mA buckpuck and then only using 35% of the current to power my 350mA LED's. In the dark however, the costume is utterly AWESOME!
As I said, if anyone needs more pics, I'm willing to take it apart! This community has helped me with several projects and I figure it's about time I contribute back!