Found a seller selling custom-made capes for the Guts Black Swordsman (pic related) and Guts Band of the Hawk figmas on Taobao.
https://world.taobao.com/item/535441613388.htm?fromSite=main&spm=a312a.7700820.0.0.0cYBrrhttps://world.taobao.com/item/535440889926.htm?fromSite=main&spm=a312a.7700820.0.0.0cYBrrThey look pretty alright and are like $7 each. I'm way too lazy to go out of my way and actually make my own so I went ahead and got one of each. Alternatively you can use figma Leonidas's cape for Band of the Hawk Guts but I don't want to spend $50 for a cape.
