This project makes two pouches from some army pants and you will also end up with some cargo shorts. Visit your army navy surplus store and go to the vintage section. Finds some cargo pants that you can convert into shorts. Choose one that has drawstrings around the ankles, so that they can be used as pull strings to close the pouch. The vintage pants could cost anywhere from two to ten USD. Go home and get out a ruler and began to measure where you want your shorts to end. Keep in mind if you plan on taking them to a tailor you will need to add an extra inch to length for the hem.
At a fabric store you will need to buy heavy nylon thread, a needle and some draw-string fasteners. If you can't find thread that matches your garment, choose a color to contrast it instead. The materials can cost anywhere from five to ten USD.
 Sew the pouch inside out. Make the stitches tight and close together. Try and keep the spaces between each stitch the same. Sewing should take no longer than twenty minutes; you will need to tie a square knot at either end of the stitching.

Possible Improvements
I intended to use these pouches for cables and occasionally personal items. If you intend to use the pouch for electronic devices you will need to sew in an extra liner. Another improvement would be to add elastic to replace the string. The last photo in this set shows a pouch with the upgraded parts.