You'll have a wonderful crop of grass'' in under a week. Cut a difficult parcel of fabric to size. You might locate these free somewhere, or they're just a few dollars to purchase new. Then there's the extra bonus of locating a treat.
Drill or cut a 'feeding' hole near the bottom, small enough that your bird's head can't get stuck in it. Next poke or drill a hanging hole in the lid. Lastly fill it with hay or paper shred plus seeds and treats throughout!