Cut your trousers to the desired short length, and thread your machine.
Measure your short leg to determine how long you need to cut two rectangles out for your cuff. Cut them twice the width plus the seam allowance. (1cm)
The height will be twice the desired cuff height, plus seam allowance. Fold your fabric in half, short ends are together, right sides together and sew along the seam allowance forming a tube.
Fold the top half of your cuff down so that the right side of fabric is showing on both sides, careful with the print placement of your fabric.
Insert the cuff into the short leg with the right side of the cuff facing the wrong side of the shorts. Line up the bottom of the cuff, pinning in place. Sew and press. Tack the cuff. Fold the cuff up on the finished length line. Hand- or machine-tack the cuff at the inseam and side seam to hold it in place
There you have it.