Take a look at the case of new engines such as the F-135:
or the F-119:
Why do they have a case with a triangular tiling pattern? Is this a new technology? A new material?
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This type of structure is called isogrid structure. Solid walls are usually very heavy and therefore engineers use more weight-efficient structures such as sandwich structures or stiffened structures with stringers and frames. A downside is the huge manufacturing cost compared to other options.
As you can see from NASA Report CR-124075 "Isogrid Design Handbook", which was written 50 years ago, it is not a new type of structure.
This is simply a way to achieve required rigidity/strength and vibration dampening with less material than in a solid, even thickness design.
Varying the weave pattern gives a relatively easy and a very efficient way to model and produce varying properties to different sections, without having to change the "base" structure thickness.
Successfully utilizing it does require advanced computing and manufacturing abilities, therefore it was not being used commonly in more ancient times.