Next, measure the thicker centre portion of your prefold and pick out your favourite adorable fabric. Here I use flannel because I like cotton. Later I might put some minky on a different one for a built in diaper cover. ;) Cut your fabric to fit the centre part of the diaper that you measured, adding a 1/2 inch seam allowance all the way around.
Run your stitch pretty close to the edge of the fabric, all the way around your rectangle. Double back a very short distance at the beginning and end of your sewing to prevent unravelling. (When I come to a corner, I stop with my needle still in the fabric, lift the foot, turn the fabric and continue along the new edge)
Cut any loose strings and voila! you have an adorable new diaper. And just in time... the baby's up from his nap and ready to wear his new custom.