What you'll need:
Faux Leather (or if you want real go for it lol)
Measuring tape/30 cm Ruler
A 16inch Zipper
A Sewing Machine
So you have to basically cut out two identically measured pieces of leather (rectangular shape). I folded the leather in half to make it easier so when I cut the shape out I can cut in half and have two pieces. I used a 30cm ruler to draw the outline with pencil. I wanted my pouch to be quite big, so I measured its width to about 16.5 inches and the height was about 12.5 iches.
Next the zip has to be attatched to both pieces of leather. Place the leather pieces on either side of the zipper fabric (which should be the right side up) to check everything is lined up ok. Then you can proceed with sewing each side to the zipper fabric.
Now that's done, its time to sew all the three sides that are just chilling lol. Its best to leave the zip open a bit just so its easier to turn the pouch in. Once thats done, all you have to do is pull the zip back and turn the bag in and wahla you have your own DIY carry all pouch! Mine definitely didn't turn out perfect but its perfect for me!
I'm not that great at explaining things so if you need more info check out anneorshine 's YouTube video :)