If you’re planning a #costume or #cosplay that requires armor, one of the most common materials of choice is EVA foam. EVA foam (in its various incarnations) is a highly versatile material that (when not subjected to too much stress) can be repeatedly worn as part of a costume if it has been shaped appropriately.
Common questions that arise with EVA foam are what type of foam should be used and where can it be obtained. EVA foam comes in different thicknesses and types and is available from a wide variety of sources. Website “Otaku and Fit” wrote a wonderful article addressing these two questions, which we highly recommend: