fallen ???? !!!
I think not SMM, you are simply
assessing your choices !
For a sewing machine cover (yeah ! Like I know all about
them !
) you will want, I imagine, some stiffocity to hold its shape, Brenda's spot on with that pelmet stuff.
Whether you want to give it some depth or softness with a layer of wadding is up too you but I too would recommend Poly for the job. I don't like it myself for quilts, wall hangings and the like but for a Sewing machine cover I think it will do a grand job!
Onwards!