Making a Pattern by Aurore Cosplay
A great video explaining the basic process of making a pattern for a body part, such as an arm.
We have the rest of her tutorial series on the Making a Bracer page.
Valkyrie Studios shared this video process of patterning and building a breastplate from a dressform.
Making a Pattern by 519geeks
519geeks shared this video on making a pattern for your armor, explaining the process for a chest piece on a model.
There is a full writeup of the process here.