I've made pillow shams, but it would work for cases too if you don't want to do shams.....you would just have to make them a little larger to accommodate the added "bulk."
Do each rectangle like a mini quilt - with backing (muslin) and a thin batting....then quilt.
RE: the inside.....The only "raw" edge you will have is the seam of sewing front and back together....and you can "french" seam that or serge/zig zag.