I just finished a king-sized one. Sewed the top to a flat king size sheet. Did some straight line stitching to keep it from shifting. My son wanted something fuzzy on the back so I got really nice non-pilling fleece from WalMart online. Envelope stitched & turned the top/sheet to the fleece. Sewed ribbons to the bottom to tie shut (my friend says that is how they close their's in Norway).