In the world we live in, global war could conceivably happen at any time. With so many political feuds and religious fanatics, people who live in populated areas need to be prepared for nuclear fallout, or at the very least, nerve gases. This instructible will show how gas masks work and is a good learning experience.

For this instructable, I will show you how I riged up an emergency M40 style gas mask. The m-40 is generally designed to filter nerve gas, primitive particles, and almost all organic particles.

Note: This filter is temporary, and is nowhere near as good as a military, store-bought gas mask. This Project was designed for a school project and was used as a learning experiance, and should not be used in actual hazardous conditions.

Lets get started.

Step 1: Materials and Tools

Most of the materials used in the gas mask are common (with the exception of the activated charcoal and the reflective foil). But for this instructable we will have a list of materials and where we bought them.

- Respirator (Used for a air-tight frame and one-way air valves) We found it at our local hardware store in the painting aisle (20-30$)

- Chemical Goggles (Used for eye covers and a surface for the reflective foil) We found it at our local hardware store next to the respirator (10-20$)

- Leather (Used for face covering and holding the goggles to the respirator) We got a small, black leather purse at a thrift shop and cut it up (1-5$)

- Reflective Foil (Used as glare and identity protection) We got this online for another project (it's really useful). It is usually sold to put on windows as it is a one-way mirror (20-30$)

- Activated Charcoal (Used as the main filtration agent because of its extremely absorbent nature) We got this at Walmart as it is used as a filter agent in aquariums (5-10$)

- Small Cylinder (Used as the filter frame) We just used a washed, tin can that we cut to size

- Wood, Cloth, and Coffee Filters (Used in the filter to separate and filter)

All of the tools used in this project are very common. But here is a list of them anyway:

- Hot Glue

- Tape

- Scissors

- Drill

Step 2: Building the Frame

The first step is to connect the goggles and the respirator. For them to fit snuggly, you have to cut off the small nose cover on the goggles. Once they fit tightly together, you glue them permanently. This is pretty difficult as you have to glue them together in the right place. We ended up gluing them while one of us wore it, to make sure it fit. We just had to be careful to not hot glue it to our face.

Step 3: Adding the Leather (Optional)

The next stage is adding the leather around the mask's rim. The leather is important because it adds to the structural integrity of the mask, adds protection to the mask, and honestly, it looks awesome.

There are 5 pieces of leather on the mask: one rectangle-shaped piece that covers the top and sides of the goggles, two triangle-shaped pieces in between the goggles and the respirator, and two pieces that cover the sides of the respirator and rim the filter holes. You can use that basic design or, just the leather into whatever shapes you want and rim the mask.

Once you have the pieces, just hot glue them on the mask. Then trim the extra leather off the sides so there is a nice curve around the mask.

You can put as much leather as you want. We didn't put that much on, since we wanted the mask small and portable.

Step 4: Adding the Reflective Foil (Optional)

The reflective foil is not necessary to the gas mask itself, but is still useful. It helps in broad daylight since it acts as sunglasses, it helps to keep your identity secret, and it makes the gas mask look both fantastic and terrifying.

The foil itself is pretty hard to get. It is not commonly sold and is even less commonly sold at a decent price. But it is worth the difficulty. We bought a huge roll and we have used it on many projects and it works and looks great.

The foil works by reflecting which ever way the light is shining from. So if you shined a flashlight at it it would be a mirror. But if you shined a flashlight through it, from the other side, you would see through it. This works great in a mask because all of the light is coming from outside the mask, whereas it is dark inside the mask.

To apply the foil to the mask, just cut a google-shaped strip out of the foil. then separate the cover from the foil exposing the adhesive. Then press the foil from the inside out onto the inside of the goggles.You can press out the air-bubbles trapped in the foil, but we left them because they didn't hinder sight and they looked cool.

Step 5: Creating the Filter

The filter is the most important part of the build because in a worst-case scenario, your life depends on the quality of the filter. But, if made correctly, this filter can be very effective.

The first part is to build the frame for the filter. You won't use the whole can, so you have to cut of the top leaving only about one fourth of the can(with the bottom still attached). Cut a small hole in the bottom of the can. After you have done that you have to build a top to the filter. We used wood because it was strong and could be sanded to the perfect size. After you have created the top and drilled lots of small air-holes in it, you can begin adding the filter layers into the frame.

The first layer you add is a layer of thick cloth. We just cut up an old wool shirt and folded a strip in. Then alternate between layers of activated charcoal and strips of coffee filter. Make sure to spread the charcoal out evenly and to fully cover the entire filter on each layer.After about two to three layers of charcoal finish with another layer of cloth and hot glue the lid into place. Make sure to glue the lid on TIGHTLY, because if the layers are not tightly packed the charcoal will roll around and fall to the bottom of the filter.

Once the lid is on, hammer the sides of the can down over the lid to make sure it never falls of.

Step 6: Creating the Filter Connector

Now that the filter itself is finished, you have to connect it to the mask. You could just tape and glue it to the mask permanently, but we wanted a consistent way to remove and reattach it to the mask. So we decided to use the airtight attachment system used by the filters that come with the respirator. So you have to fit the small, notched ring that comes on the store-bought filters onto the homemade filter. We did this by making a smaller cylinder that will connect the filter and the ring.

You can make the cylinder by wrapping a strip of wire and then gluing it into a solid cylinder (you might be able to do it with PVC). Then just glue the plastic ring on top of the wire cylinder, and tape the whole thing. Then glue it and the filter together and tape them together, and you have a fully removable filter.

Step 7: Necessary Details

You could build two filters and have both of them on the mask at the same time; we didn't though because it is impossible to shoulder a gun if the filter is in the way and two filters don't add any filtration to the air. In fact, having two filters just means you will have to replace twice as many filters.

But with only one filter you have to plug up the other. To plug it up, just put tape and glue on both sides of the unused hole until air cannot pass through it.

Once you have plugged up the hole successfully, you can do any final details to the mask. Like covering the flat part of the filter in tape and punching holes in it. Or any final adjustments to the straps so that the mask is airtight when you wear it.

Step 8: Done!

Your done with your very own gas mask! Whether you are preparing for the apocalypse, dressing up for Halloween, or just trying to scare your neighbors you have a somewhat--functional, awesome looking gas mask! We think that this gas mask can filter a decent amount of airborne particles..

This mask is extremely cheaper than any good bought one. The cheapest official M40 gas mask we could find with a filter is about 450$. This cost us about 40$.

I hope you enjoyed our instructable!