I have a very unique approach to helmet design and I thought I'd show off exactly how I bring Halo's most famous helmets to life. I chose the Trailblazer helmet to show off my workflow, as the commissioner of the piece was very interested, so if you find this interesting, you have studleyavocado to thank!
Gathering Reference
The first thing I like to do is gather reference files.
Surasia's spartan pack is a great place to do this as it provides all the armors and attachments in the game.
I select the helmet I want and export it as an STL. I then import that STL into Onshape.com, my preferred CAD program.
This allows me to have the perfect 3D model reference to ensure I get the perfect proportions when modeling the helmet.
Creating the Bust
The first step of actually modeling the helmet comes in the form or creating a completely solid bust of the helmet. This really just needs to capture all the big major shapes and components. Any details will be more easily captured once the bust is a solid part.
There is no right way to approach the bust making process. I will often go with a mixture of solid parts and surface creation. Once I can fully enclose the surfaces I can create a solid part to merge with the other solid parts to eventually end up with my fully solid bust. In the picture below you can see a little bit of every part of my bust creating work flow.
First I like to use the vertex points as reference for creating 3D spline curves that I can use to make completely smooth surfaces. This is how I manage to give all of my models completely smooth surfaces devoid of creases. As I connect all these surfaces I can close them to create solid parts that will all be combined into the later bust.
For symmetrical parts like the cheeks you can also use things like lofts to connect the space between the surfaces to easily create your solid portions.
Here you can see the solid bust piece is not every single piece in the helmet solidified into one.
Parts that I know will end up being separate and removable (like attachments or removable parts like the mandible gas filters) can be modeled separately and not added to the bust. This is because the whole point of the bust is to contain the head and therefore must fit the entire head cavity without having any spots that are too thin to be structurally strong.
Hollowing out the Bust
Hollowing out the solid bust is an important part of the helmet making process as this will determine how comfortable the helmet is, how strong it is, and how the helmet will fit about the head.
I will cut the helmet into cross sections and sketch ovals within those cross sections to ensure that I can get the largest cavity possible without ever leaving any walls of the helmet too thin. This will usually leave me with a cavity boolean that looks like this
I will take this boolean and subtract it from the solid bust to make my initial bucket
At this point, I can also remove the front surface of the visor to make the visor hole for later.
Slicing the Bucket
The next part of my process is what makes my signature style of helmet making. Slicing the bucket into separate parts to be individually printed, sanded, and painted.
First I identify natural seams in the helmet that would make for good places to cut the helmet.
On this helmet, one obvious one is the brim of the larger upper bucket portion. It was not perfectly flat, but was comprised of two flat surfaces. This is also a spot where thinking ahead helps as I specifically modeled these parts to be perfectly flat earlier when I made the bust.
Additionally I will look to project natural concave creases outward into surfaces that can be used to slice models perfectly along seams. This is how I eliminate hard to sand concave creases appearing in most of the individual pieces of my models.
Connecting the pieces
The last piece in the process of creating my helmets is ensuring that the sliced helmet can be assembled easily and mostly friction fit pieces. This allows the helmet to be assembled and visualized in its many desired configs before any permanent adhesives are applied, if required at all.
There are many different methods I employ to allow my helmets to interlock and securely be put together. The simplest relies on the clean slices I made earlier. By simply extending some of those faces into larger pieces, pieces such as the face place can simply fit inside of larger pieces.
Similar to the above method, you can separate pieces on the helmet going through all the way to the inner cavity so that it will slot into place on a completely self contained hole
For some additional security with these shape fitted insert pieces, you can also add some alignment features. You can see for this central vent piece, I add two circular alignment features.
In conjunction with the above method, or for completely flush faces, you can also employ separately printable pegs. Circular pegs will more easily fit into their slot than square pegs just based on machine error/tolerancing but obviously may allow some rotation. So when choosing your peg shape, you can either use multiple pegs or oval shape pegs to prevent too much rotation. For this helmet I went with two cylindrical pegs to connect the face and cheek plates.
As we get to pieces that we want to be interchangeable, we need to expand to some fancy methods of attachment. for the removable gas filter boxes, I use a hinge latch similar to the kind you see on battery pack covers. I then combine this with a 3d printable hollow screw filter to make sure that this part is secure without ever needing any glue.
Speaking of 3d printable screws, I also employed a nut and bolt hint system for the overhead UA attachments and you can see how that method allows for a removable rotating joint.
Lastly, the final method I will often employ is the use of magnets. I try to stray away from magnets where I can, as that requires additional hardware outside of what can be printed. You can see that I use them for most of my neck seals for my helmets and some of my attachments such as the CBRN Module on the Commando helmet, or the AIRWOLF attachment for the Trailblazer helmet.
For the AIRWOLF attachment, I utilized two 20x3mm disc magnets and it is important to include physical stops to prevent the magnets from sliding around but more importantly keep them separated. It can be hard for glue to adhere to 3d printed walls, so if you are relying solely on glue to keep the magnets connected to their components, you will often find the magnets popping out and stick to each other rather than their respective pieces.
Tolerancing
One small thing to think about once you have split all your pieces or during the splitting process, is how loose or tight do you want your pieces to fit together? In my experience, .25mm gaps between touching faces will allow the actual 3d printed pieces (with all of its inerrant machining error) to actually fit together with little to no sanding.
While you are adding these small gaps to your prints, one other thing to consider is the wall thickness. In my experience 2mm is the thinnest you want any part of your print to get. This is the point of no return for physical strength and will still potentially give you troubles when sanding if you are not careful (you can overheat the wall and warp the print if using electric sanders.)
Prototyping
Lastly, we get to the fun part, printing the helmet. The nice part of 3D printing, is that it is the quintessential rapid prototyping tool. Keep adjusting your models as you notice short comings in your models. Are some of your pegs too short? too weak? are there not enough? Is it causing your pieces to flex undesirably? Are your tolerances not large enough, making your prints impossible to fit together? Was the piece too difficult to print with how you printed it? Did you see a way to remove some unnecessary supports by just slightly modifying some edges or overhangs in the model? These are all questions I am constantly asking myself and reiterating upon when I print my helmets. Whenever I prototype a helmet I just designed, I usually end up printing 2 of every piece. My first attempt almost has some small feature I would like to tweak to ensure I am putting out the best product possible and make sure that there is way less headache on the customer end of assembly of my helmets/props.
If you want to see how this all ended up, you can read about my build of the Trailblazer here