Props Assault Rifle kit project w/sound and display


Better late than never, right?

It took me long enough, but I've finally finished working on an Assault Rifle cast I got from Justinian almost a year ago.
The casting I received from him was near flawless- I had barley any filling and sanding that needed to be done which was great. I requested one of his hollow castings as I wanted to put electronics inside of it.

For electronics I wanted to include a display counter and if possible a sound system. Due to the size and profile of the AR I figured I wouldn't be able to put in a very large speaker, but still I really wanted to see if it was just possible to do, period.

Justin made his AR kit into modular parts, and they fit together like a glove after a little sanding. The only other work that needed done to the raw parts was drilling the hole for the barrel and the flashlight, and the holes for the wires so they’d have a conduit to run through.

Once I had the body work done (which hardly took any time, like I said, Justin really outdid himself with this) I began to play with how the pieces would fit together. I knew that once they were together I would have a hard time painting the seam and trying to get painters tape into some the finer areas would be a pain, so I went ahead and primed them and then gave them their main base coat for color.

The colors I used for this project were
-Krylon flat Black (lower receiver/grip)
-Krylon Satin Nickel (middle section)
-Rustoleum Dark Steel (upper receiver)


After they had a couple layers of their main colors painted, I started the assembly process. I decided to use JB Weld (a simple 2pt epoxy) to hold the pieces together. TO make this easier, I took my dremel and carved a channel in each piece on the joining surface and also scuffed up the surface to promote better adhesion. It also helped with keeping any spill over minimal when the pieces were pressed together.


After a day of waiting for the epoxy cure, I drilled the hole for the barrel and flashlight. Then it was time for the really fun part- the electronics.
My go-to for this part of the project is 405th regular thatdecade. First, I gotta tell you that he was a pleasure to work with through this whole project. Whenever I had a question (no matter how simple) he was able to answer it or help me work out a solution. There were also a couple of times I ran into somewhat large setbacks and he was able to help me out. He's probably as happy as I am this is done so he doesn't have to deal with me anymore :p

After I reached out to thatdecade and told him what I was planning to do, he was able to hook me up with a prototype for his new ammo counter display kits. The kit itself is pretty frickin cool- it has a trigger switch, a counter reset switch and an illuminated power switch. This is all ran off a standard 3 AAA battery pack.
When powered on, the counter starts at 32. When the trigger is pulled and held or pulsed the counter depletes to zero and can be reset by pushing the reset button. From there the cycle begins again.


If you've got an Assault Rifle, Battle Rifle or DMR prop I HIGHLY recommend one of his kits to take your prop to the next level. Speaking of the next level, the next thing I wanted to do with the kit was add sound.

Since this was more of an experiment for me I didn't want to spend too much money on a sound kit. It also would be required to run off the battery pack for the display counter so I didn't have a lot of options to work with. In the end, I decided to go with an inexpensive kit from for about $20. This kit has one small speaker that while not the loudest, would serve this purpose and also ran off a 3 AAA battery pack.

After getting the software for the board so I could program it I began feeding it sound files. I decided to use the Halo 4 assault rifle sounds because it sounds so meaty and since I had one small speaker I wanted to sound a ferocious as it could :p .

Once I was satisfied with the sounds, I began to tackle how to integrate the sound board with the ammo counter board. I removed the battery pack from the sound board and then wired the board into the counters power source. Okay, so the boards both had power and could be turned on by the switch, so that was good. The next task was figuring out how to get the sound to play when the trigger was pulled. I figured out pretty early that I would just need to take the signal wire from the sound board and connect it to the trigger. When I did that, and pulled the trigger the sound loop would play but the counter would not do anything….hmmm. I knew I must be missing something simple but for the life of me I could NOT figure out what it was. I was starting to get frustrated so I consulted thatdecade to see what he thought and he informed me that I forgot the ground wire on the sound board (d’oh!).

So after a little rewiring, that ended up being exactly what the problem was. Now when the trigger was pulled the sound would play with it. Here is a sample of it during the testing phase (I apologize for the cell phone quality recording; it sounds much better in person).

Now that I had the wiring down it was time to start inserting the electronics into the AR cast. Fortunately, the holes I drilled earlier were large enough that they made feeding the wires pretty easy.
The sound board and battery pack would be installed into the AR’s fore grip section, and would be accessed by a removable section that stays held in place with magnets. To keep the battery pack and sound board from rattling around I used a couple pieces of Velcro to hold them to the inner walls.

Here are a few pics during that phase of the project




The speaker would be installed in the middle section of the rifle. For there to be any sound at all, a hole would need to be drilled or exposed somewhere so the sound could come out and be heard, otherwise it would be muffled and impossible to hear.

I figured the best place to put it would be the vent slots where the barrel is. I only had to cut a hole large enough to match the diameter of the speaker. After I did that though I realized I wasn't satisfied with the way it sounded when it was in there. To make the most of it I fashioned a small cone around the speaker to focus and maximize the sound as much as possible. It just so happened that a paper towel roll was the perfect size for the speaker so I simply cut one down to fit and glued it in place. After that the quality was much, much better.

wub wub wub wub

inserted into place, starting to take shape

To conceal the hole I made in the middle section I took some speaker cover from an old netbook I had lying around. I cut it to size and then just super glued it over the vent slot. I think the result was pretty good!


The next section to install was the display counter itself. This was pretty challenging as there was a lot to fit into that small section. Initially I wanted to put the ammo counter right up and flush with the edge of the hole, but the casting here was pretty thin and I didn't want to risk removing too much material to make it fit, so I settled on pushing it back about ½ an inch or so. Not my first choice, but it works.

I also had to fit the 4 green LEDs into this section- these LEDs are on the side of the gun just below the counter. They were 3mm in size and to hold them into place I purchased some led holders from a local electronics store- it was $1 well spent haha.


I painted them and drilled holes just large enough to they’d insert into place easily. Once they were in and the LEDs clipped in I added a little hot glue to be safe.


Things were going really well at this point so it was only natural that I’d have a major setback :rolleyes
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Part 2: the maddening.

Part 2: OMG Why must life be so hard?

This is how I was at this point
I feel your pain, dude.

Included with the counter kit I got from thatdecade was a transparency overlay to simulate the blue color and hud elements on the Halo AR. I had just finished cutting the shape of the overlay and as I was going to install it a drop of superglue fell onto it. I’m not quite sure if it was the glue, the heat or even a combination of the two but when I wiped the glue away it wiped away the ink with it :( :( :(


I was going to attempt to save it with a blue sharpie but when I got to it the next day, it just got worse. I have no idea if it was the heat or something (it has been abnormally hot lately) but after that it just started rubbing off.


After a few minuets visiting Sad-Town, population: me, I contacted thatdecade and he was kind enough to send me a replacement (a few actually) which got me right back on track. Being extra careful this time, I glued it against a piece of thin plastic I took from a clam-shell casing to give it some support and then glued the cap onto the end of it. I’m pleased with the result and in the dark it looks really good.

(I don't have an image of it yet but I'll update it when I do)

In normal indoor lighting it looks good as well. The only thing that is a little unfortunate is that since the sound kit is wired into it, when the trigger is pulled the intensity of the light is dimmed a bit. Before I had wired in the board it was quite bright through the whole sequence. A necessary evil I suppose.

The last two electronic components to add are the trigger and reset switch. The trigger was easy enough, I just had to hollow out the section deep enough to recess the trigger into- that trigger would later be pressed by a piece of laser cut plastic to press the switch to engage the counter, so if you followed that, a trigger to push another trigger haha.


I didn't have a good plan for the reset switch. Ideally what would have been cool is to wire it into the magazine receiver of the AR so that when the magazine was pulled and reinserted it would engage the button and thus simulate the action of reloading. While a good idea, I just couldn't pull it off like Justinian did in one of his builds.

The reset button was a little bulbous and trying to make it work in that section would have required me to do a lot of cutting and I was too worried I’d break something that I couldn't fix, so I had to think of something else. I settled on putting it in the spot where what I *think* is the AR’s safety switch.


I had easy access to this location from hollowing out the trigger slot earlier, so that was a plus. The button fit in there perfectly- the only thing I had to do was hack off a large piece of the plastic insert button that Justinian had included. Once I did that I just hot glued it into place and I think it came out really well! Now to reset the counter you just push the button- it’s nice too because my thumb can easily press it when I’m holding it.


Then I had to marry those sections together; it was pretty challenging trying to pull the wires through the hole while not getting epoxy everywhere.


Now that the electronics were in it was time to move to the finer details and accessories. I painted the barrel and then glued it into its slot. For the flashlight I used a simple $3 one from Harbor Freight. I ended up drilling the hole a little deeper than it needed to be so to correct that I glued a piece of EVA foam onto the end to push it up a bit. This also had the benefit of allowing me to push in the flashlight just a tiny bit to actually turn it on which is pretty cool. Now I don’t have to take it out just to turn it on haha! :D

The next section was the magazine. Justin had included the option to slice off a piece of the magazine and replace it with a bullet to give it a cooler look, but I decided I didn't like it; In real life there is no way that magazine could hold 32 rounds (let alone 60 for the CE version) so while cool, I decided to just leave it as is. I painted it flat black but to give it a little more detail I painted the bottom part Rusteoleum Metallic Black. Doing this helps the magazine to pop out a little when looking at it surrounded by the flat black of the receiver. To hold the magazine in place, I went the easy route and just velcro’d it in. It can still be removed and inserted back in should I want to pop it out. I'll add a couple pics of this if anyone wants to see it, but I think its fairly self explanatory.
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Part 3: Home stretch!

Part 3: Home stretch!

Now that everything was assembled, I touched up any areas where the paint got dinged and then proceeded to fill any gaps in the seams. While the rifle was solid and holding together, there were a couple areas where slight gaps had occurred. While no one else might notice them, I knew they were there so of course I had to obsess over correcting them. After a lot of thinking and having previous bad luck with adhesives, I decided to just use plain old Elmers glue. I filled the (thinner than a credit card) gaps exactly like you would if you were using a caulk gun. I had to wait a few hours for it to dry but I’m glad I did because something very curious happened in my favor- the Elmers glue apparently absorbed some of the color or something from the painted surfaces so I didn't have to worry about painting a few white strips! It was really cool!

The next thing to do was take a few pictures of it in its clean and pristine condition!




Here is a clip of what it kinda sounds like assembled- I think the microphone might have been covered when I recoreded- I promise it doesn't sound this wimpy in person

The last thing to do was to give it a little black wash. I mixed a healthy amount of Black acrylic paint with a few dabs of yellow and grey and then thinned it with liberal amounts of water. Then I just brushed it on in areas where the gun would be most likely to get grimy, waited for it to dry a little and then wipe it away.

I am pleased with the results.



In this picture you get a good view of the speaker mesh I used to cover the sound opening. I think it also adds a nice touch and would look great even if there was no speaker there anyway.

So I think my project was a success. I was able to incorporate display AND sound into an AR casting, and while the sound is not the greatest, I’m convinced that it IS possible to do. If that middle section was a little more hollow towards the back I probably could have fit a second speaker in and even added an amplifier in the hand grip to boost the output (there was still plenty of room, even with the battery, sound board and wires). Though, now that I think about it, it would require a little more battery power and likely redoing resistors etc but I’m pretty optimistic. Maybe someone reading this will be able to do that and take this kind of prop even further!

I hope you enjoyed reading this :)

A big thank you to Justin for the casting and a big thank you to thatdecade for the display kit and moral support during all my goofy mistakes :D



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Well-Known Member
Awesome job! That really turned out great. Good assembly tutorial as well. I will refer people to this if they need help.


It looks like it was just pulled out of a weapons rack. So cool. And the working counter. Going to sub this for the future. Thanks for sharing!


Thanks for the Kind words gentleman, I had a lot of fun working on it.

The only thing left to do at this point is make a display stand of some sort. I've never done any wood working or plastic work before so this should be an interesting challenge.


New Member
It looks awesome and I'm sure it sounds good too even with one speaker. my only question is does the counter always go to zero even once the trigger is released? Or can the trigger be pulled in bursts and hold an accurate count?


It looks awesome and I'm sure it sounds good too even with one speaker. my only question is does the counter always go to zero even once the trigger is released? Or can the trigger be pulled in bursts and hold an accurate count?
The trigger can be held down for bursts and the counter will be accurate, so yes you can pulse the trigger for that effect.

The really cool thing about this board is that thatdecade programmed it to be able to fire in 3 different modes: single shot, 3 round burst and full auto. This means that his kit can be used in a DMR, BR and AR prop :)


Well-Known Member
Love the way it turned out, and am jealous of your weathering paint job. AWESOME WORK

Does that sound board have a standard 3.5mm headphone jack? Maybe you can use one of those portable pocket powered speakers made for phones and mp3 players.

edit: Double checked, it does have a standard headphone jack. Run an extension cable to a larger powered speaker mounted on your suit. BLOW people AWAY with SOUND ~!


New Member
The trigger can be held down for bursts and the counter will be accurate, so yes you can pulse the trigger for that effect.

The really cool thing about this board is that thatdecade programmed it to be able to fire in 3 different modes: single shot, 3 round burst and full auto. This means that his kit can be used in a DMR, BR and AR prop :)
That's awesome! Thanks for the info


Amazing work, think about all the minds that will explode at the next con or Halloween outing you go to with this thing! Nice job!


does thatdecade have a site for the his kits or are they in the classifieds? Most epic work btw :)


does thatdecade have a site for the his kits or are they in the classifieds? Most epic work btw :)
He does actually, but you'd be better off asking him directly. He is active in these forums. Check the first page in this thread, he commented so you should be able to see his profile and send him a message :)


New Member
Did you say this was a kit you ordered off somebody? I need a weapon or a good tutorial how to make a foam one. Gratz it looks amazing! love the led ammo display!


New Member
Can u send me it :D? All i need now is the assault rifle cant find one anywhere nor ones i could build with foam. Would rather pay for one then make a junky foam.