inspired by many "how to instructions" from instructables i made mobile pouch from old jeans.
for that i used
old jeans
lace
scissors
needle
thread spool
3D outliner (fabric color)
fabric glue
sequins for decoration

Step 1: Cutting and Sewing

place your mobile phone on jeans leg's bottom (choosing leg's bottom so that we will get readymade one side stitched)
cut a piece such that you will have 2 inches material above your phone and 1 inch below in height
width should be twice your phone width plus 2-3 inches (you may take more)
i have cut big piece to hold my headphone too
now fold it from reverse side and sew the open ends of the piece leaving top end open (refer pictures)

Step 2: Adding Lace

when sewing is done reverse the pouch
since we have chose proper part of jeans we have ready made stitched side on the top towards opening
now as shown in picture cut the top side from ends (plz refer photo)
cut 2 pieces of lace whose length should be twice the width of your pouch plus 3-5 inches
now add laces as shown
use matching lace ( i have used white only to demonstrate)
tie a knot of lace as shown
when you pull these knots(with lace from both sides) your pouch will close (this technique works good with thin denims/thin fabrics)