This takes me back many years .....................
Cut a circle of fabric (plastic was what was used way back) that is broader than your shoulders.
Split in the centre with a hole in the centre that will fit your neck.
(Kind of like a mini Christmas tree skirt).
Then use a piece of bias binding to sew around the neck hole, with enough extra on each end to tie together to close.
Of course as quilters, we would probably make it into a mini quilt .... quilt it up and bind the outside edge of the circle too.