Halo 4 Helmet ( Size A, B, C )

3D printable Halo 4 Master Chief helmet in various sizes...

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This project will cover detailed instructions and commentary around all three sizes of the 3D printable Halo 4 Master Chief helmet.

I started this project to learn my way around Autodesk Fusion 360 for modelling ( free for hobbyist use ) and my Replicator 2.

STL files and existing instructions are hosted on thingiverse at...

Adult Size A -
Medium Size B -
Small Child Size C -

Size B and C are self contained designs with all mods built in.

Size A has additional designs that were added along the way, and are advised to get the latest model. I might consolidate these at some point.

This is discussed further in project logs below, there are more

Right now, go and look at each project log entry for design details, as I work out how best to use hackaday projects, there are presently 5...

  • Assembly order

    big_red_frog02/10/2016 at 01:50 0 comments

    Noting I don't cover magnet inserts in these images, it is just a quick and dirty assembly order for a helmet made with large parts. plastic inserts for back fan and lights are also not shown.

    Start with a jowl and rear bottom piece

    Attach together

    next take a temple and top piece, in this case a printed as a single large part

    Attach to form a full side

    Repeat for other side

    Now take the roof and back piece, ( back fan and back bottom printed as one large piece )

    Attach to made one long center piece

    Add a full side as assembled previously

    Then the other side

    Add the peak

    Now take the three chin pieces


    Attach to main helmet

  • Addition parts for the Adult Size A

    big_red_frog03/04/2014 at 03:43 0 comments

    If you are going to print the Size A, you need to understand which extended design parts are available to print...

    The size A evolved as I worked the design, there are additional parts available that are either exclusive to the size A or have otherwise been combined into the base model for the size B and C

    Chin Front with M4 bolt modifications - Those M4 Hex heads really up the game.

    Perforated Visor for Halo Helmet - want to be able to see through a printed visor?

    Halo 4 Helmet Size A Big Pieces - Combined components where separation was unnecessary if you have a replicator 2 size build volume.

    Halo 4 Helmet Full Size A with tiewraps - take control of that wiring harness, with built in tie wrap "warts" in the inside of the model.

    Halo 4 Helmet Full Size A Peak with Batteries - you need somewhere to put those 9 volt batteries, and these built in clips rock.

    Want a PETG vac formed clear visor ready for painting in your favorite metallic?

  • Wire routing with tie wraps

    big_red_frog03/02/2014 at 22:03 0 comments

    Print in place tie wrap mount points for wiring guides

    Note the parts at and

    Are replacement parts for the size A model. They were designed after the main model was completed.

    Size B and C have all these features in there base model already.

    They have simple "warts" in the walls to allow the insertion of tie wraps, you can then use these to route the wiring from the jowl and rear insert LED's up to the 9 volt battery in the peak which mounts in a print in place sprung clip.

    The present lighting circuit is very simple, soldering the resistor in series with each pair of 5mm LEDs. The resistor can sit directly between the LED's themselves, which makes soldering the twisted pins easy.

    Here is a Jowl Led insert, two 5mm LED's and a suitable current limiting resistor in series back to the 9 Volt battery.

    Here are the rear insert LEDs, with contacts taped off. Same combination of two 5mm LED's and a current limiting resistor.

    Note all three pairs, 2 Jowls and the rear insert are wired in parallel to the 9 volt.

    Here is the Jowl on the other side, which wires straight to the peak to join up with the other runs.

    I originally put an in line switch in the design, but it was more trouble than it was worth, and pulling the battery connector off is the preferred form of control at this time...

  • Tension pins and cleaning out the pin holes

    big_red_frog03/02/2014 at 14:56 0 comments

    The use of tension pins allows components to be accurately aligned for gluing or in use assembly such as the chin parts.

    This also allows you to print split surfaces as flats, which helps.

    I have used tension pins purely because I knew I could get them. 3mm filament is close enough to 1/8 inch diameter, so you could just as easily cut lengths of such to use, or any other material with a nominal 1/8 diameter.

    Two lengths have been used in the various models.

    Size A Adult uses 3/4 inch pins throughout as per 240-025 - 57 off, just buy a box of 100 from your local hardware supplier, I get mine from Spaenaur here in Canada. These are stainless and shiny, not necessary, but, they ARE shiny...

    Size B Medium and Size C child uses 5/8 inch pins throughout, as per 240-008 at the same link above, 46 off, again just buy a box of 100. They are a little shorter and fit in the curves more easily when remodeling down to size. There are fewer pins in these sizes, as many of the parts are combined as they now fit in the print area of a replicator 2.

    They can also be bought from Amazon, not sure on those prices and delivery though. ( really, find a local hardware supplier, a real one, not a big box store who will happily charge you a dollar for 2! )

    3/4 length.

    5/8 length

    Here is a picture of a 5/8 pin next to a magnet and coin for scale, no banana was available at the time.

    When printing with support it is likely that various holes in the model will end up with webbing inside them, if they are horizontal or facing down, that's fine though, the material is intended to be removed, and should give, without damaging the main body.

    You will need a 1/8 diameter drill bit on a hex mount as per

    Stick it in a screwdriver handle for hex bits, and you have a grunging tool to get in and do some dentistry.

    Then just push in to each hole and clear out the naughty plastic. Some will already be clear, some will be easy, some will have a personal vendetta against you. Start gently until you get the hang of it, if the bit is sharp, it should be doing the work. You should be able to feel when you bottom out, and try not to drill through the end of the hole and into the main body. Its not the end of the world, but try to avoid it!

    Each pin hole is deeper than the pin needs to allow some detritus to be left, test fit a pin and make sure it goes at least half a length in. You can then pull them back out with pliers if necessary. In final assembly you will likely glue them in place.

  • Taking the rear insert to the NeoPixel Max

    big_red_frog03/02/2014 at 03:19 1 comment

    First dimensionally accurate model a 16 led Neopixel ring from adafruit to OCD level 1 because you can...

    The led

    The ring

    Then define a body space gap with the model so you can use it as a boolean operator against the piece you wish to mount it in.

    Design a test piece to test the body space fit.

    Print it, low material use compared to final part, so you can afford to iterate...Be amazed when it fits like a glove the first time.

    Model it directly into the target part...

    Print it ready for integration. Shame the print is not quite as glassy...

    Prototype your electronics.

    Stick it in and press go... Very hard to video....

    No easier to video when in the helmet, trust me, it looks fab...

    Of course this means I will have to place an Arduino nano into the helmet peak next to the 9 volt. Good thing i already have a model for that!

    to be continued.

  • 3D printed vac form mold for visor

    big_red_frog03/02/2014 at 03:03 1 comment

    Original STL files are hosted in thingiverse at

    As if by magic model a form for the visor in the original model.

    Work out where your cut lines are

    By looking where it intersects the main model.

    Once you have the model, print it.

    Spray it.

    spray it some more

    Have pull handles and screw locators for the peg board

    Then pull in pairs out of PETG so the webbing is on sacrificial areas, having first sprayed some furniture polish for easy release.

    But first of course heat it on a quartz heater hot box that you can collapse for storage and transport

    remove the molds with a bit of compressed air down the side

    Cut out with metal shears, its just safer, easier and more accurate than a band saw. Add magnets and drop in place.

    Next step is to paint the visor, but that's another adventure...

View all 6 project logs

  • 1
    Step 1

    Step 1 test - these instructions are to test layout / intent of hackaday projects.

  • 2
    Step 2

    step 2 test

  • 3
    Step 3

    Step 3 test

View all 4 instructions

Enjoy this project?



PolyPrintYT wrote 09/12/2022 at 13:31 point

hey!how many pins and magnets do i need? And where can i order them

  Are you sure? yes | no

deuce wrote 04/13/2020 at 00:44 point

how many of the pins do you need and where did you order them

  Are you sure? yes | no

gregorykoga21 wrote 10/13/2018 at 02:37 point

what size is the adult helmet. My head is 11 inches / 279.4mm in the length and I didn't see anything saying what size it was please help. 

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roadrunner74578 wrote 08/27/2017 at 05:20 point

What size tray are these ideal for?

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raozuhair wrote 05/26/2017 at 03:51 point

Dunno if I missed it, but how much filament does it use (size A)

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ronwalters36 wrote 04/06/2016 at 03:35 point

Is it possible to buy a couple vac formed visors from you? I was going to print the mold and mac a vac form bed, but it was a 30 hour print... or if there is a standard one out there that fits, can you send a link? Maybe some sort of paintball visor would fit


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ronwalters36 wrote 04/04/2016 at 17:46 point

Does the visor go in after everything is put together? Or will it need to be put in before the 2 halves go together?

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big_red_frog wrote 04/04/2016 at 19:19 point

snaps in at any time with magnets.

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Nathan wrote 03/16/2016 at 21:40 point

Is it possible to make one large enough to assemble over a basic motorcycle  helmet

  Are you sure? yes | no

big_red_frog wrote 03/16/2016 at 22:10 point

Anything is possible. However, it would be  very big if you were trying to print for clearance.

Practically you would be better off boolean'ing out the motorcycle helmet and printing the parts to stick on.

Quite a lot of work unless you had a very good model of the donor helmet.

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mcallinan wrote 06/11/2014 at 14:28 point
Are you considering creating stl files for the rest of the Halo armor? Several of my students are looking at this site: and trying to figure out the best way to make the rest of the suit. We're hoping to make different sizes (S, M, & L) like you did with the helmet. (Great JOB, BTW!!!)

  Are you sure? yes | no

big_red_frog wrote 06/11/2014 at 22:38 point
There is a huge gap between a basic export of domain parts to something that is sized right and printable. Like many things on thingiverse, it is interesting source material, but not really a "thing".
I would love to have the time to take this on, though not necessarily with the same sources, but real life issues prevent me from having the time ( lost job, found new job, ramping like crazy )
I am limited to getting some really good paint jobs on the existing helmets at the moment as the only point I can push.

If your students take it on, then I know I would be a thankful end user like many others.

Choose a single part, with a reasonable size to start, and go for it.

If you can make a glove adornment correctly, then everything is just more effort :-)

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Idealist! wrote 04/05/2014 at 15:44 point
How much would you sell one for? And any way to make it the original color, with visor?

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big_red_frog wrote 04/05/2014 at 17:01 point
I have been asked this before, and settled on 250 dollars, with visor, pins and magnets, first finish, so removal of major support, but would need further work to paint. No electronics.

For original color scheme, as per the vac form, it takes automotive primer / filler, color and clear very well, so any color / finish you can buy in a can.

Haven't got round to trying metallic on the visor yet...

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Idealist! wrote 04/06/2014 at 13:14 point
Ok cool! Well thanx for the info. One day if I have the extra cash I will contact you for sure. Keep up the good work!

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Mike Szczys wrote 03/04/2014 at 16:16 point
You sir, are some type of wizard. Absolutely amazing work on these. I see from your profile that you hang out in marshlands most of the time. What I'm really wondering is if you use these skills for your work or if this is purely hobby-acquired mastery?

Peg and magnet connectors shown in the instruction steps are great. I was not familiar with "slotted spring tension pins before". Thanks for detailing that part in your build logs!

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big_red_frog wrote 03/04/2014 at 19:39 point
Day job is embedded software in telecoms domain, you'd be surprised how much call there is for it in the lower lying wetlands.

Hadn't touched CAD in a decade or more, but dove into Fusion 360 when I bought a Replicator 2. So we are growing together.

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Riftillionflux wrote 03/02/2014 at 21:08 point
oh my lord i love you, im going to try and make this as soon as i get my 3d printer up and going!

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