First you make your pattern.
Preemie- 2.5" long, 1.5" wide for bottom of shoe. 1.25" long, 1.5" wide for top of shoe. 2"x4" for cuff.
newborn- 3.5" long, 2" wide for bottom of shoe. 1.75" long, 2' wide for top of shoe. 2.5"x4" for cuff.
infant- 4.5" long, 2.5" wide for bottom of shoe. 2.25" long, 2.5" wide for top of shoe. 3"x5" for cuff.
Round the edges of the top and bottom of shoe. Stretch should go across the width of the shoe and the smaller measurement of the cuff.
cut out pieces
Fold cuff pieces in half and sew(right sides together). Fold cuff in half, hiding the seam on the inside.
Sew top of shoe to bottom of shoe, right sides together. Only sew along the outside, rounded edge.
Line seam of cuff(folded in half) up with back of shoe, with cuff inside the inside out shoe.
Stretch seam and sew, lining up with back of shoe and top of shoe as you sew.
Flip shoe right side out and fold cuff down.
I choose to sew these but you can serge them also. I just feel it adds bulk on teeny tiny sizes.