When used correctly, this small prop can produce some pretty darn awesome effects. Fueled by nitrocellulose, it can shoot a fireball (that can travel for about 2-3 meters), or something like glitter. Besides being super cool to fire test shots, it can easily be concealed for use in a movie.

This special effects shooter can also be used to create magnificent light paintings, such as those found above.

This is the third and final part of a series of instructables. Go check out the other two parts The Reusable and Wireless Ignitor(part 1), and Nitrocellulose(part 2).

Warning: I'm going to keep this short and sweet:

This is solely designed for special effects in videos or for photography, not as a toy.
It doesn't affect skin (even when lit), but the fireball should still not be fired at another human being without proper safety measures [safety glasses, fire-proof clothes (if shooting at clothes), fire extinguisher near by, and someone watching]

Step 1: Materials

Part	Supplier
RC car glow plug	(Amazon)
AA battery	(Most stores)
AA battery holder	(Radioshack)
Limit switch	(Mouser)
1/4" - 32 Nut	(Mouser)
1/2" Copper tube	(Home Depot)
1/2" Push nut	(Home Depot)
Alligator clip	(Sparkfun, Radioshack)
Flash Cotton (nitrocellulose)	(Make it yourself , Aliexpress)
2 Velcro cable organizer straps	(Amazon)

Tools:

Stranded wire (~22 AWG at the thinnest)
Soldering iron
Solder
Drill
Sanding drill bit or belt sander
Hacksaw
Metal file
Rubber wristbands
Epoxy (optional)

Step 2: Setting Up the Pipe and the Cap

Cap

Drill a 1/4" hole in the cap for the glow plug (it doesn't have to be centered)
Secure the glow plug with a 1/4" - 32 nut as shown in the pictures
Sand part of the lip off so it can lie flat on your wrist
File any sharp edges

Copper Pipe Use a hacksaw to cut about 6cm of the copper piping (be aware this will make a really loud and high-pitched squealing sound). Then, file the edges down.

Step 3: Wiring It Up

Overview: This circuit uses the 1.5V DC from the AA battery to make the platinum wire inside the glow plug glow red (or even white!) hot. The glow plug isn't constantly on because of two switches in series: the safety alligator clip must be connected to the tip of the glow plug, and the limit switch must be pressed.

Important note: The glow plug requires so much current that the wires must be pretty thick. This and a dead battery will be important to note when you are trying to find a problem in this project. Even breadboard connections are too thin!

The Wiring (everything is also described in the pictures)1. Solder one of the wires from the battery to the middle switch terminal
2. Solder a wire to the normally open terminal of the switch
3. Strip the other end of this wire and feed it through the cap, and secure it with tape if desired
4. Solder a wire to the other side of the battery connector
5. Attach an alligator clip to this wire and wrap it with electrical tape to prevent shorts (this will act as a safety for loading and storage)
6. Cover all solder joints (especially the battery) with epoxy or hot glue to prevent a short and for comfort

Step 4: Putting It All Together

Optional: use epoxy to secure everything as shown in the pictures (the epoxy will most likely break, as mine did, but it provides good support)
Use the two Velcro cable organizers to bundle everything together as shown in the pictures (there are very helpful picture comments)

Step 5: Preparing for Firing

To fire the special effects shooter, you will first need to load it with the propellant (lightly packed nitrocellulose). To do this, use a pencil to push the nitrocellulose all the way down the barrel.

Next, gently roll some nitrocellulose into a small ball (~1cm diameter). This ball will be ignited by the propellant and turn into a fireball. But, this ball can be replaced by anything, such as glitter or small glow-in-the-dark beads for a cool light painting.

Then, cut a 40cm piece of string (or fishing line if you want it to be invisible), and create an adjustable knot (you can use the pictures as a guide).

Finally, secure it to your arm with two rubber bands (or any elastic bracelets).

Step 6: Fire It Up!

1^st picture: A light painting of me shooting it straight up
2^nd picture: Yet another light painting
3^rd picture: A GIF to show how easily it can be concealed

Here is a video of it in use:

A GIF of me doing a kamehameha:

And here I'm am dodging a fireball (example of how it can be used in a movie) (I realize how weird I look XD):

Don't forget to vote if you liked this instructable!

Credits:

http://makezine.com/projects/fireball-shooter/: the design demonstrated here contains different parts and isn't meant to be concealed very much, but it is a pretty good project nontheless. (check out my comment below for a full explanation)

Introduction: Special Effects Fireball Shooter