Halo Infinite - House of Warriors Concept Helmet

Here is the Halo Infinite Concept Helmet with Optional Hat add On. It's basically a modified halo 5 scout helmet. The helmet is sized for a 24" head but you should always double check sizing for yourself.

My best advice is take time to size it to your body. For instance, measure your forearm (bicep to wrist) while it is bent at a 90 degree angle. Your forearm armor should not be longer than that at that measurement (actually shorter to account for wrist movement).

Other people (not me personally) use a paid program called armorsmith which creates a mannequin of yourself on the computer using your measurements. Then you take in each piece of armor and size accordingly.

If you are cheap, like me, learn Blender.

Import this model from CG Trader into it (https://drive.google.com/file/d/1NEFAIgIIZ4z5zokPO1fGxme3742hFu4R/view?usp=sharing),
take the same pose as that model and have someone measure your height.
Then scale the model till it gets to that height.
Repeat that process for chest thickness and scale accordingly
Next, import your armor pieces into Blender and virtually size/scale until you like what you see.
Then, export the models and print.