Worbla’s a great material to use to make fantastic armor for your SD and MSD Ball Joint Doll.
Tiriaq (note, link NSFW) made this 1:3 scale armor set for his SD
Archangeli made this Valkyrie version of her Dollfe Dream Sasara Kusugawa, and even shared a writeup on the process here!
Dirili used Worbla for various pieces of armor, and included a tutorial on how to make some for your own BJD here!