Could you make one by cutting out the shape using a piece of the material circuit boards are made of? How about Delrin or Nylon plastic sheet? Look here:
https://www.google.com/search?q=delr...hrome&ie=UTF-8
"Starboard" used in marine applications would also work. It can be cut to shape really easily.
Plastic supply house have it. We used to use it all the time in our metal shop machine shop classes. Great stuff. Comes in white and black. Leaves a very smooth cut edge and can be filed easily to shape. You could probably get a scrap piece at no cost.
https://www.acplasticsinc.com/inform...stic-varieties
Look here:
https://www.google.com/search?q=who+...hrome&ie=UTF-8
Read this thread. There is a fellow in post #2 (Curti) who has that part.
https://forums.aaca.org/topic/302219...r-motor-parts/