Introduction: EVA Foam Prop Blaster Tutorial

By
About: Design/Process Engineer who loves to make things

I have been wanting to jump into the world of foam prop making for quite some time now, so this Instructable is going to map out my first attempt at making a prop blaster out of EVA foam. I have some experience in modifying and painting Nerf blasters when I was younger that will hopefully help me with this project. In the past year or two I have discovered several YouTube channels including I Like To Make Stuff, Punished Props, and Andrew DFT that show how to make really cool looking props using EVA foam. Foam is a great material for making props since it is inexpensive, comes in many sizes, and is easy to work with. If you are thinking about making projects using foam, you should definitely browse these channels.

I Like To Make Stuff: https://www.youtube.com/user/iliketomakestuffcom

Punished Props: https://www.youtube.com/user/punishedprops

Andrew DFT: https://www.youtube.com/user/punishedprops

Step 1: Tools & Materials

Materials:

- Foam floor mats (11 mm thick)

- Foam sheets (2 mm thick)

- PVC pipe

- Hot glue (contact cement or super glue are also other options)

- PlastiDip

- Spray paints

- Brush paints


Tools:

- Varying sizes of blades/knives

- Scissors

- Hot glue gun

- Dremel (rotary tool) & bits

- Sandpaper (various grits)

- Paint brushes

- Painter’s tape

- Paper / white board

- Rulers, pencils, pens, markers

- Cutting mat (I didn’t use one but it would be nice to have)

- Hair dryer (heat gun is better)

- Disposable gloves

- Respirator

Step 2: Disclaimer

As you can see in the section above, this Instructable utilizes several tools and materials than can be harmful if used incorrectly. Knives are sharp, rotary tools can be dangerous, heat guns and hot glue can burn you, and paint, dust, and adhesives are not good for your lungs. Please use caution and ask somebody for help if you do not feel comfortable doing something.

Step 3: Planning & Research

Planning out your project is a vital step that allows you to organize your thoughts and actions. This generally makes the project go smoother, and it helps to reduce the risk of missteps.

I started this project by doing lots of research on foam prop building. I searched through all of the YouTube channels mentioned in the introduction section for any videos that included tips and tricks for foamsmithing as well as tutorials for specific builds.

After rewatching these videos, I made sure I had all of the necessary tools and materials. The main thing I needed to buy was the foam itself. Foam floor mats are pretty inexpensive and very easy to find at home improvement stores, craft stores, and online. I was able to find large 2’x2’, 11mm thick interlocking mats at the store 5 Below for $3 per mat. I also found a pack of 9”x12”, 2 mm thick foam sheets at the store A.C. Moore for $12. The pack had 54 sheets in nine different colors which was a pretty good deal. I also picked up extra Xacto blades since you want really sharp, clean cuts.

Once I had all the necessary tools and material, I gathered an enormous amount of reference material to help me design my blaster. I scoured Google images for foam blasters, sci-fi blasters, and real firearms to draw inspiration from.

Step 4: Templates

After I picked a few designs I liked, I needed to figure out the dimensions of the blaster. I did this by tracing an airsoft pistol and measuring it to determine the proper scale. You can use paper and pencil for this, but I used a large 3’x4’ whiteboard that gave me a lot of room to work with. Another great thing about using the whiteboard was that I could very easily modify my drawings without leaving marks all over it. It also allowed me to trace the airsoft pistol and then alter the drawing to look like my designs. This was awesome since it made keeping the correct dimensions really easy. After I sketched my designs, I traced them onto paper and cut them out to make a template.

Step 5: Foam Cutting

I decided to make the upper part of the blaster 3 layers thick (33 mm) and the lower part of the blaster 2 layers thick (22 mm). The thinner foam sheets (2 mm) will then be used to create more detail and give more depth to the prop. In order to trace out the parts onto the foam, I cut the paper template into its main parts, separating the upper part, the lower part, the trigger, and the sight pieces. Something to take note of is the textured side of the floor mats. In some cases this texture can be useful to create some really cool effects, but for this project I wanted the smooth side of the foam on the outside. This means I had to flip two of the templates over so that the textured side was on the inside. I pinned the templates to the foam using thumbtacks, putting them as close to each other as possible so that I could maximize my use of the foam. I then traced the templates onto the foam using a pen.

When you cut out your foam pieces, you want to make sure that your knife is very sharp. A dull blade will catch on the foam and pull on it, creating tears in the edge. Also, try to keep the blade as perpendicular to the foam as possible. Later on we will add bevels to some of the edges, but keep it perpendicular for the first main cuts. You can use a small Xacto blade or a larger knife, or even something like a hot wire or scroll saw to cut out your pieces. I also found that using a metal straight edge helped to keep the blade from wandering and angling. I found that using a larger blade and cutting all the way through the foam in one pass left a better edge than trying to use a small blade and make multiple passes.

Step 6: Internal Strengthening

Now, this next step is optional, and I’ve only seen this done on a few occasions, but I really wanted to try out a bunch of techniques since this was my first project working with foam. This step involves cutting channels in the interior of the foam to add some sort of strengthening material. I can see this really helping if your design includes long, thin sections that could flex easily. During my research phase I saw people using pencils and other materials, so I decided to use some mechanical pencils. After removing any remaining lead, I unscrewed the tips and pulled out the insides to leave only the plastic tubes. I then cut the tubes to length and drew on the foam where I needed to cut out the channels to accept the tubes. I tried to cut the channels to roughly half the depth of the tubes on each side of the foam so that the tubes would sit in the middle. With the support tubes glued in one half of the foam and the channels cut on the other side, I hot glued both halves together, trying to get glue as close to the edges as possible. Hot glue is pretty forgiving as far as alignment goes, so I was able to move both halves until they were lined up as close as I could get them. You could also utilize this technique to put metal rods or some other heavy material into the foam to give your prop some more weight.

Step 7: Foam Shaping

Now unless you were perfectly accurate cutting out your templates and your foam pieces, you’re going to have areas where the layers don’t match up. This can be fixed by utilizing some sandpaper and especially a Dremel or rotary tool with a sanding or grinding bit. Be careful when doing this as it can take off quite a lot of material (too much if you’re not careful). Also please wear a respirator when doing this! You don’t want to breathe in foam dust. With the edges cleaned up, I started to add bevels to increase the level of detail. I did this by drawing lines on the two adjacent faces that were going to be beveled, and then cutting the foam across these two lines. Taking the blade out of a box cutter made this much easier. I use the Dremel again to smooth out these beveled edges as well as round over some of the other edges that I wanted to be more gradual. The final aspect of shaping was to contour the handle so that it was more comfortable. This was a process in trial and error, and I made sure to go very slow.

Step 8: Adding Detail

Next, I added more depth and detail by using the thin foam sheets. I sketched out some ideas on the large paper templates from earlier, made new templates of these details, and then traced them onto the thin foam sheet. I also traced these new templates onto the body of the blaster so that I could align them properly when gluing. Another cool technique you can use with foam is scoring and heating it. When you use just the tip of your knife to score the surface of the foam and then heat it with a heat gun or hair dryer, the cut opens up and gives you another form of detail and added dimension. I drew these lines onto the foam and then heated them until they opened up. With all the detail lines heated and opened, I glued on remaining pieces like the grips, top rail, and sights.

Next, I started filling in the seams between the layers with more hot glue. I laid a small bead of glue on top of the seam, lightly dipped my finger in some water, and then smoothed the glue down into the seam. The water keeps the glue from burning you and from sticking to your finger. Now I’m sure this isn’t the best way to fill in the seams, but I already had the glue gun heated up, and it’s a technique I’ve done before. As long as you take your time and get the glue down into the seam, it will look alright, especially after it’s painted and weathered. A better option would probably be to fill the seams in with some sort of caulk or body filler.

After this, I moved on to the barrel. I found two sizes of PVC in my scrap collection that were an appropriate size for this blaster, and I cut and glued them together to get the look of a suppressor. I drilled holes in the PVC and added two strips of thin foam to add some more detail. I traced the end of the pipe onto the front of the blaster and then worked with a blade and a Dremel bit to cut out enough material for the pipe to slide in snugly. To complete the assembly process, I glued the barrel into the upper section of the blaster.

As you have noticed, I chose to glue everything together before the painting process. This means that I had to use a lot of painter’s tape to achieve my desired paint scheme. You could also paint all of the details separately and then glue them all together. This will reduce the amount of taping you need to do, but then you run the risk of having exposed, unpainted glue peeking out from under your parts. Choose whichever method you think will be best for you.

Step 9: Sealing

In a lot of the tutorial videos I have watched, I have seen people run a heat gun over the entire surface of the blaster in order to “heat seal” the foam. This basically tightens up the pores in the foam and creates a smoother surface. As I do not own a heat gun, I used my hair dryer to complete this process to the best of my ability. The main problem with this step is that the heat caused the hot glue in the seams of the blaster to melt. In order to keep this from happening and getting leaking glue all over the blaster, I only did a little bit of this heat sealing. This would not be a problem if you used contact cement, some other type of adhesive, or high temperature hot glue. The next step in sealing the foam and prepping it for paint is to spray on a few coats of PlastiDip. PlastiDip is basically a liquefied rubber substance that you can get in a spray can at most home improvement stores or online. It applies the same as spray paint, but it dries as a rubbery film. This is great for getting into the pores of the foam which creates a great bond and a nice surface to apply your actual paint to. I sprayed on 5 thin coats (might be overkill), letting it dry for 10-15 minutes between coats, until I got good coverage and a nice surface.

Step 10: Painting

Once the PlastiDip is dry, you can add your actual paint. I chose to use spray paint, but you could also use brush paint if that’s your preference. I used painter’s tape to mask off areas I didn’t want to paint so that I could apply several different colors. Make sure you let your paint completely dry before you apply masking tape, otherwise you risk pulling off paint with the tape when you’re done.

Step 11: Final Details

Using foam can give you a great level of detail in your projects, but it can’t do everything. In order to add another level of realism and really make your blaster pop, you can add some final detail pieces made out of different materials. I used screws, switches, buttons, and plastic pieces from old toys to add some more dimension and functionality to the blaster. Be creative here and see what works for you! It may be smart to plan out these details prior to painting if you need to cut or glue anything that may be problematic with paint already applied.

Step 12: Weathering

Weathering is an optional but really fun part of this project. If you want your blaster to look shiny and new, simply add some clear coat to your paintjob and you’re done! If you want your blaster to look like it has been used and abused over the years, then weathering is what you’re looking for. This is basically a process of painting that mimics the appearance of dirt, rust, grime, and general wear-and-tear on your blaster. Weathering is an art form in itself that takes practice to look realistic without going overboard. The good news it that it’s really hard to mess up since it’s supposed to look “bad”. It also hides a lot of imperfections in your foamsmithing and painting. If you want tips and tricks on weathering, check out this link or do a Google search for tons of helpful information online. I did this step after adding the final detail parts and pieces so that I could weather them as well. It would look weird to have a dirty, worn blaster with shiny new parts. Once your weathering is complete, spray some clear coat on your blaster and you’re done!

https://www.youtube.com/watch?v=B9QhOABTGoM

Step 13: Conclusion

This entire project was completed over the course of 4 days. This was mostly due to taking pictures and doing this write-up along the way as well as waiting for paint to dry. The actual foam construction can be completed in one day. This Instructable is by no means an exhaustive description of building props with foam. There are plenty of other great techniques and additional features that you can research and utilize in your own builds. If you’re feeling really adventurous, try adding 3D printed parts, using stencils for painting, or even adding electronics like LEDs or speakers to your blaster. Go wild and make it unique! Overall I am really happy with how my blaster turned out considering this was my first project using foam. I learned a lot during the process, and I have a bunch of plans for future (bigger) blasters and even helmets and armor! Hopefully I will be able to document those builds and post them here!