This is a cute idea! It's a doodle duvet cover! Buy here for $76.11. Or try to DIY it. Use regular fabric. Draw paper lines and holes with permanent markers and a ruler. Spray with Scotch Guard. Then have the kids write with washable markers intended for fabric (be sure that they are intended to wash out of fabric, some are only designed to be washed off of surfaces like walls). Wash when needed.