As Halloween was approaching, and our local doggie daycare announced their pet Halloween costume contest I was trying to figure out what costume to make for my dog Jericho. At some point I realized that since Jericho is black, and you can't see him at night, some sort of contest involving light would be perfect, no to mention extra safe.

Then I thought about how we have LED strips, I decided on an LED spider. The LED strips almost touch the ground so they look like moving spider legs. I have a video at the end of this instructable.

After going through the process of making this costume I realized that it would also make a great decoration. Rather than attaching it to a pet harness, just attach a string and hang it up.

In the first step I will go through all the materials needed to make the LED spider, both as a costume and as a decoration.

After that I will go through preparing the box, preparing the strips, setting up the electronics, and putting it all together.

Step 1: Gather Materials

The first step is to gather all of the materials and tools you will need to make the costume.

Materials:

- 8 LED Strips

Alternatively, if you are find with doing a lot of soldering you can get a roll of strips and cut them to the desired length and solder on the connectors. This method would definitely be a lot cheaper.

- 1 clear box

I used the Digilent project box because I happened to have one. It has thin enough walls to cut through, but stays securely shut. It is also the correct size to sit on my dogs back.

- Clear Small Zipties

They don't necessarily need to be clear, since this will mostly be seen in the dark, but it looks nicer.

- Clear Spray Paint (Optional)

In one version of this costume I sprayed the clear box with clear spray paint so that it looked cloudy. I found this helped diffuse the light better so the box looks more like one shape rather than a bunch of dots.

- Solid Core Wire

You'll need wire to do the bread-boarding for the LED strips. Solid core is easier to use with breadboards. It would be best to have at least 4 colors of wire so that you can differentiate between the different signals, i.e. power, ground, data, etc. The wires from this wire kit work really well for this.

- Half Size Breadboard

A half size bread board will fit best inside the box and obstruct less light, plus you only need a few rows.

- UC32

This will tell the strips the color and brightness.

- 8, 3-pin headers

To connect the strips to the breadboard.

- 4 AA, Battery Pack

To power the board and strips.

- AA Batteries

Tools:

- Hot glue gun and Hot glue

- Sharpie

- Paper

- Calipers

- Exacto Knife

- Drill

This isn't required, but starting the holes with the drill makes it a lot easier.

Step 2: Measure the Widest Part of the LED Strip

In order to make sure the holes in the box are big enough to stick the LED strips through, you will need to measure the widest part of the LED strips.

If you are using the waterproof WS2812 strips. The widest part is the connector, which has dimensions 14mm x 7mm.

Step 3: Calculate Where the Strips Will Go

Next you will need to figure out the distance between the strips so that you can place them evenly on the box. I made the distance from the edge of the box to the strips slightly less than the distance between strips.

To do this I took the width of the box and subtracted 4 times the led strip width, because there are four LEDs, and divided that by four to get four even spaces.

so,

(box_width - 4*(led_width)) / 4 = space_width

However, I need 5 spaces, but two of those can be smaller so I divided the space_width by two for two half size spaces. You can see all these marked on my paper in this image.

Measure and mark on a paper those measurements.

Step 4: Mark the Holes on the Box

Using the paper with the measurements, mark the cuts on the box that you will need to make.

Step 5: Cut Out the Holes for the LED Strips

Using an exacto knife, cut out the holes for the LED Strips. It makes it a lot easier if you first drill the corner of the square out, so the first cut is already made.

Be careful not to put your finger where mine is in this image, you will cut it. Trust me, I learned.

Repeat this for all of the holes on this side of the box.

Step 6: Repeat Steps 4-5 for the Other Side of the Box

Repeat Steps 4-5 for the Other Side of the Box.

Step 7: Cut the Strips to Size

If you try to use the whole length of the strips, the battery pack can't supply enough current, so you will need to cut them shorter. I cut my strips to a length of 11 LEDS and that seemed to work out well.

Be sure that you cut off the correct end. The end with the arrow pointing away from the connector is the one you need to connect it to the board.

If you want them to remain "weather-proof" you'll need to seal the ends. I did this by squirting a little bit of hot glue in the cut - end of the strip and cutting off the excess.

Step 8: Set Up Your Breadboard for the LED Strips

To program the LED strips, since they are all going to have the same thing on them, we can use one data pin. We also only have one 5V and GND pin we can use for the LED strips. This means we have to use the breadboard to make 8 spots, with power, data, and ground on the breadboard.

The Fritzing image for the breadboard is shown above as well as my completed breadboard.

The blue (on the Fritzing image) or orange (on the physical breadboard) wires, connect the two sides of the breadboard together. This way we can spread out the strips on either side.

The red wires connect all of the nodes that need to have power. The black wires connect all of the nodes that need to have ground, and the green (in the Fritzing image) or white ( on the physical breadboard) connect all the nodes that need to be data.

Your final breadboard should look like the Fritzing image attached to this step. The green, red and black wires going off the edge of the image will eventually connect to the board.

Step 9: Program the Board

If you have never worked with the WS2812 LED strips, you'll need to install the library as shown in this instructable.

If you already have the library installed you can open the code attached to this step in MPIDE and program the board. Be sure you have selected the UC32 as the board, and the correct port.

I've attached both the pde file for MPIDE and the text file of the code.

Step 10: Connect the Breadboard to the Board and Power

Next you'll need to connect the breadboard to the board, and power the board.

The green wire coming off the breadboard goes to pin 4.

The red wire coming off the breadboard goes to 5V0.

The black wire coming off the breadboard goes to GND.

The red wire from the battery pack connects to Vin.

The black wire from the battery pack connects to another GND.

Plug the 8, 3-pin male headers into the breadboard where the LEDs go. This is labeled on the Fritzing image and shown plugged in on the breadboard picture.

Before you put the costume together plug in the LED strips, paying careful attention to the orientation of power and ground. Make sure the LEDs show the correct pattern, and they all light up. If your board keeps power reseting which causes the strips to turn off and on, they are drawing too much current. Either decrease the brightness or number of LEDs.

Step 11: Affix the LED Strips to the Box

Put the LED strips through the holes, so that the hot glue end is outside the box.

Pull them far enough in that only 5 LEDs stick out of the box.

Drill a hole on either side of the led strip, through the bottom of the box. make sure these holes are very close to the side of the box.

Put a zip tie through the holes and around the LED strip to affix the LED strip in the desired position.

Step 12: Repeat Step 11 for All Strips

Repeat step 11 for all strips

Step 13: Attach the Strips to the Inside of the Box

Using the same drilling and ziptie procedure, attach the end of the strips that go inside the box, to the inside walls of the box. Make sure there are strips facing outwards touching the sides, top, and bottom of the box. This will provide the effect of the body of the spider.

When you do this, be sure that the connectors can get close enough together that they will be able to reach the breadboard.

If you want to help the light diffuse better, at this point you can spray the outside of the box with clear spray paint to create a clouded effect.

Step 14: Attach the Harness (For Costume Version Only)

If you are making this as a costume for your dog you will need to attach a harness to the box.

You can use the same drill and ziptie procedure. Make sure you test it periodically so that you know it will sit right on your dog.

My dog Jericho happens to be the same proportions and size as a sprite bottle, so I used that for initial testing.

You may also want to make a hole in the top and bottom of the box for the leash to attach to the harness.

Step 15: Final Assembly

Put the breadboard, UC32, and battery pack in the box and plug all of the various components together. Close the box, being very careful of the circuits inside.