After seeing the 2016 Ghostbusters, I decided to make a Holtzmann costume for Halloween.

This pack is made mostly of cardboard and PVC pipe. The lights sweep through a spiral of red, hold briefly, go dark and repeat.

Step 1: What You'll Need...

Supplies:

Lots of cardboard

Black, copper and silver spray paint

Black and yellow electrical tape

Straight pins

Fishing line

Strainer

Ball valve (like any of these https://www.lowes.com/search?searchTerm=ball+valve...

1' braided vinyl hose (like this: https://www.lowes.com/pd/B-K-3-4-in-x-1-ft-Reinfor...

Strand of neopixels from adafruit (https://www.adafruit.com/product/1460) I bet you can find other brands, but this is what I used, and I was really happy with them.

Microcontroller (I used an arduino)

Battery pack to power lights and arduino (I used this one https://www.adafruit.com/products/771)

3 AA batteries

PVC pipe (1/2" diameter x about 5' and 1 1/4" diameter, about 2')

Small breadboard jumper wires

1000 µF capacitor

2 alligator clips

3-6' of wire (I used some speaker wire I had. This is purely decorative, so it doesn't really matter what you use)

Solder

Zip ties

An old backpack you can cut the straps off of

Soda can

Tools:

Soldering iron

Box cutter & craft knife

Hot glue gun

Drill

Heat gun (you can probably use a hair dryer for this step if you don't have a heat gun)

Ratcheting PVC cutter (or a saw if you don't have a cutter)

Can opener

Step 2: Build the Frame for the Pack

I began by cutting the base of the pack out of cardboard.

I folded the right side and the bottom to create flaps that served as a base to glue down a box that I folded for the bottom of the pack.

Before hot gluing the whole thing together, I spray painted it with a coat of black, followed by a lighter coat of a metallic silver to make it look more like metal.

Overall dimensions: 12" wide by 20.5" tall; the overhanging ledge on the top edge is 3" deep.

The bottom box at the base is 12" by 7" by 5" deep.

The piece on top is 11"x5" on its face and 1" tall. It slants outwards on the sides to meet the larger box below.

Step 3: Build the Wand

For the wand, I used two sizes of PVC pipe (1/2" and 1 1/4") that I cut down to size using a PVC cutter. The thinner pipe, I cut to 11" and the wider one I cut to 17".

Once I had the pieces cut, I drilled small holes along the end of the wider pipe (5 rows of 7 holes each).

I used a small, folded piece of cardboard and some zip ties to hold the two pieces together and built a small box of cardboard to go around the pipes where they were attached.

Once I liked the shape, I gave everything the same paint job as the frame.

To get the grips, I wrapped the wand in twine to get the shape, and then covered the twine in black electrical tape.

On either end of the wand, I stuck a piece of plastic I had lying around (there are a lot of old pieces of broken things in this pack- nerf gun parts, broken sprinkler pieces etc. For yours, look around and see what you've got. Any kind of industrial-looking plastic will probably work.)

To make the rest for the wand, I cut open a soda can, using a can opener to remove the top and then scissors to cut off the front. I taped the edges so no one would get cut, drilled holes in the bottom and attached it to a small piece of PVC using zip ties. This whole thing I spray painted and attached to the base using more zip ties. (**note- I had to attach this to the base of the frame before gluing down the large box at the bottom of the frame.)

Step 4: Program the LED Strip

The lights I used are from adafruit. (https://www.adafruit.com/product/1460) I ordered two meters. They'll send it to you in the longest stretches possible, so I didn't need to connect two strands to each other.

I downloaded the adafruit neopixel library and used one of their sample codes as the base for mine. I altered the color and the timing.

I've included the arduino file of the code I used as well as a video clip of the lights running that code, so you can see how the lights in the pack look when they're on.

Step 5: Wire Arduino and Lights

When uploading the code, the arduino is powered through the USB cable, but I wanted this to be portable. I split open a couple jumper wires and soldered them together and taped up the intersections. This way, I was able to power the arduino and the LEDs using one battery pack.

(more notes in the images)

Step 6: Attach Lights to Pack

I used some packing foam as the base for the lights. I cut it into a hemisphere shape with a box cutter and hot glued it to the frame.

Then, I used straight pins to pin the lights down in the spiral shape. I laid the strainer over that whole setup. The strainer isn't attached to the pack. It's held in place by the two pipes that I laid over it next.

At this point, I added a strip of yellow electrical tape and drew lines on it for the hazard tape.

Step 7: PVC 'copper' Pipes

Before spray painting the pipes that lay on top of the strainer, I used a heat gun to warm them up until they were flexible enough to bend into these shapes.

The lower pipe is 20" the upper one is 16".

Once I had them in a shape that looked like the packs in the movie, I spray painted them copper. When they were dry, I used hot glue to glue them into place. I noticed as I wore the pack that it would flex and the glue sometimes cracked loose, so I ended up using a loop of fishing wire around the pipe and up to the ledge on the top of the pack to make sure the pipe stayed in place if the glue came loose.

I added the handle here, just a ball valve you can get at any hardware store. I used electrical tape to attach it to the piece of braided vinyl and hot glued them both in place.

At this point, I also added some hooks to the side of the wand and the edge of the pack, to serve as a rest for the wand. I got those pieces off a broken plastic toy. I used a dremel to cut them off and hot glued them to the pack.

Step 8: Finishing Up

I really liked the radioactive heart decals from the movie, so I made my own using electrical tape and sharpies.

I found a picture online and used that to make a stencil.

I had some speaker wire that I used zip ties to attach to the end of the wand and to the ball valve on the pack.

I scavenged the straps off an old backpack and used glue and straight pins to attach those to the pack. They did have a habit of falling off if I was too rough on the pack, so I might try a stronger adhesive, like superglue, next time.