So I improvised a loom with some prefabricated frames I purchased at Michael's. There was a selection of various sizes, and I went with 18 inches because I am only weaving the sleeves. The neck covering I will knit up.
I first started by wrapping my yarn neatly around the frame. Any sturdy frame would do I suppose....
Dylan took this photo of me weaving on the floor:
After a few hours, I have the beginnings of fabric that I could use for my costume: