Cut a 12-by-12-by-6-inch triangle up all four side seams on a pair of boot cut jeans that you've turned inside out. The base of the triangle should be even with the hem line.
Cut four large triangles that measure 12-by-12-by-20 inches out of double knit fabric.
Sew around the edges of the double knit with a zigzag stitch.
Pin the double knit so that the printed side of the knit faces the wrong side of the jean fabric.
Sew the double knit to the jeans with a 5/8-inch seam. It is not necessary to hem the bottom of the double knit fabric.
Measure the bottom triangular portion of the collar on a cotton dress shirt. Use this measurement to elongate the collar length.
Mark a section of double knit fabric that measures the same width as the triangular section of the collar. Your new collar should be the same width as the existing collar, but about 2 inches longer.
Cut two double knit triangle collar sections. Glue the fabric onto the top of the existing collar.
Remove the existing hem of your dress shirt. Cut the bottom section of the shirt so that it is completely straight across.
Measure the bottom of the shirt and cut a 3-inch wide section of double knit that measures the length of the shirt plus 1 inch.
Pin the right side of the double knit onto the wrong side of the shirt tail. Sew the knit into place. Make all your seams on the underside of the material. Hem the bottom of the shirt with a 5/8-inch hem.