EVA Foam Prop Bullpup Blaster Tutorial

Recently I posted an Instructable on making a prop blaster pistol out of EVA foam. This was my first attempt at a project using foam as the main material, and I learned a lot throughout the process. The finished project was pretty good, but I wanted to construct another larger prop blaster and make several improvements.

This Instructable won’t go into quite as much detail on the construction process as my previous one, so if you’re new to working with foam, check out that project here:

https://www.instructables.com/id/EVA-Foam-Prop-Bla...

Since I already made a prop pistol, I wanted to make something a bit larger this time around. I decided to make a bullpup style blaster since it is bigger than the pistol, but not quite as big as a full size rifle. I’ll get to the rifle (and hopefully sniper rifle) later :D

Materials:

Foam floor mats (11 mm thick)

Foam sheets (2 mm thick)

PVC pipe

Hot glue (contact cement, spray adhesive, super glue are also other options)

PlastiDip

Spray paints

Brush paints

Acrylic sheet

Screws, washers, buttons, zip ties, electronic components, etc...

Tools:

Varying sizes of blades/knives

Scissors

Hot glue gun

Dremel (rotary tool) & bits (sanding drum, cutoff wheel, etc…)

Sandpaper (various grits)

Paint brushes

Painter’s tape

Paper / white board

Rulers

Pencils, pens, markers

Cutting mat

Hair dryer (heat gun is better)

Disposable gloves

Respirator

Paper towels

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.

The planning stage this time around was basically the same as in my last Instructable. After rereading tips and tricks on working with EVA foam, I compiled an archive of images of sci-fi blasters, real firearms, and the like that all shared the bullpup aesthetic. A “bullpup” design basically means that the magazine is located at the rear of the blaster, behind the trigger. This allows for a more compact design. My final design ended up being basically a copy of the NERF Rayven toy. With my design picked out, I started the fun part, building!

I used my large white board to trace the handle and trigger area of an airsoft pistol, so that I could get the scale for my design. Next, I used my reference images to sketch out the rest of the body of the blaster, adding in some basic details. When I was happy with how it looked, I traced the design onto paper and cut it out to create my templates. During the design phase of this project, I decided how many layers thick each section of the blaster would be and labelled my templates accordingly. Using different thicknesses is a great way to add depth and realism to your designs.

After tracing the templates onto the foam, I cut out all of the necessary pieces. Be careful when you trace your templates onto the foam, since you’ll need to flip some of them over so that the textured side of the foam doesn’t end up on the outside. While cutting out the pieces for my last project, I mostly used a small Xacto blade, making several shallow passes through the foam. Unfortunately, this made it hard to get nice perpendicular cuts. It also had a tendency to tear the foam instead of cutting it, even though I used new, sharp blades. This time around, I used a larger blade or box cutter and cut all the way through the foam in one pass. This gave me really nice, perpendicular, flat edges with no tearing. For more intricate cuts, I went back to using the smaller Xacto blade.

Even though my cuts for this project were significantly better than my last attempt, there were still areas where the different layers didn’t quite line up. I used my Dremel with a sanding drum to even out these areas as well as any spots where the foam had a rough surface. Be very careful using a rotary tool on foam since it eats through it really easily! A belt sander would also work really well here for getting perfectly flat edges. Some high grit sandpaper worked well to further smooth the surfaces and remove any little foam burrs that were sticking out. I also found that a pair of scissors worked well to clean up edges.

After the initial clean-up, I added bevels or chamfers to a bunch of the edges of my pieces. I did this by drawing lines on the two adjacent faces of the edge that I could cut along. I took the blade out of my box cutter and used it to cut these bevels. This is shown more clearly in the image provided. Once again, be extremely careful when using a sharp blade out of it’s handle! I then made a second pass with my Dremel and sandpaper to smooth out these surfaces.

I wanted other edges to be smoother, so I used my Dremel to round them over. The grip area of the blaster took a while to get perfect, but I kept sanding and checking it until it felt comfortable in my hand. Once all of the pieces were cut and shaped, I glued them all together. I chose to use hot glue for this because I had it on hand, but you could also use spray adhesive or contact cement.

Next, I added more depth and detail by using the thin (2 mm) foam sheets. I sketched out some ideas on paper, made templates, and then traced them onto the foam. 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 a more defined line.

After this, I cut a small length of PVC to use as my barrel. I then traced the outer and inner diameters onto the foam and proceeded to cut out the section in between the two circles so that the PVC would fit in snugly. The barrel was then adhered with hot glue.

I also made a sight for this blaster with both thicknesses of foam and some sheet acrylic. I made paper templates before tracing, cutting, and gluing it together. I cut the acrylic squares with my Dremel and a cutoff wheel.

Next, I started filling in the seams between the layers. I tried to get glue as close to the edges as possible during the initial glue-up, but I inevitably ended up with gaps between the layers of foam. I chose to use hot glue again to fill in these gaps. 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. As discussed in my last Instructable, this probably isn’t the best way to fill in the seams, but I didn’t have caulk or any other type of bondo or body filler on hand. I was a lot more careful this time to only get glue down into the gaps. After I was done and everything had dried, I went back and cut away any excess glue.

Before painting your props, you should “heat seal” your foam. This process involves running a heat gun over the entire surface of the blaster in order to tighten up the pores in the material. This allows for better paint adhesion as well as a smoother finish. Using a hairdryer on its highest setting seemed to work pretty well for me, but a heat gun is the best option. The next step in the sealing process 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. Normal paint soaks into the foam without actually covering the surface, but PlastiDip adheres to the foam while also laying on the surface. 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. Once dry, spray or brush paint will adhere to it.

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 sprayed on 5 coats of tan until it completely covered the black PlastiDip. I used painter’s tape to mask off areas I didn’t want to paint so that I could keep certain areas black. Make sure you let your paint completely dry before you apply tape, otherwise you risk pulling off paint with the tape when you’re done. If you want to be extra cautious, you can press your strips of tape onto your shirt or a table and then peel it off and apply it to your prop. This makes this tape less sticky and less likely to pull off your paint. For areas that I wanted to be black, I actually just kept the PlastiDip. PlastiDip comes in a wide variety of colors, so you could do the entire paint job with it if you wanted to. I will say that I have used PlastiDip in other applications, and it does have a tendency to wear down in areas where it is handled frequently. If you choose to keep your grips painted with PlastiDip, I would highly suggest spraying clear coat over it to prevent this.

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, LEDs, buttons, springs, washers, and electronic components 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.

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. I used a combination of different colored washes and dry brushing to achieve the finished look. Once the weathering was complete, I sprayed on a few layers of flat clear coat to protect my paint job. I chose a flat clear coat to go with the military style paint job, but you could also use a shiny clear coat like in my last Instructable to achieve a different look.

This entire project was completed over the course of about 4-5 days. I designed the blaster and cut all the foam pieces in one day, spent about 2 nights shaping the foam and gluing parts together, and then 2 more days painting.

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 it turned out, and I think I definitely improved upon my last project! I’m planning on making more foam blasters later this summer, but for now I will be taking a break from foamsmithing to work on some other projects. Stay tuned!