I've been making these cases for earbuds for a while, they are are also really good for spare change etc as they can be clipped onto a bag etc. I make mine out of oilcloth as I like the strength of the fabric and it holds it shape really well, you could make them out of any fabric but you may may need to line the cases or use interfacing to give the case some shape. You can see how this pattern developed here
Cut 2 squares out of the oilcloth - I cut my squares 10cm using a pinking rotary cutter as I like the finish, but its not essential as oilcloth doesn't fray. The zip is a 4" zip
Sew the 2 squares onto the zip as shown, lining the second one up with the first one
It should look like this when you have finished.
Clip and sew 2 sides of the square - leave the zip closed while you do this and leave the side closest to the zipper open
It should look like this when done, with the zip partially open
If you want to add a ribbon tag with either a trigger fastener or split ring, then now is the time to do, you will turn the case inside out so place the ribbon tag on the inside of the case as shown and hold it in place with a clip as shown (Oilcloth shouldn't be pinned, but if you don't have wonder clips you can use paper clips or binder clips)
Bring the zip seam across to the clip holding the ribbon tag and clip it in, this will give you the shape of your case.
Sew across this seam - take your time sewing across the zip to make sure it stays in place, trim ends of zip if needed and cut loose thread. You can also trim the corners to help it sit better.
Turn inside out and admire your lovely new case.
You can also buy finished versions of these cases on my website
This is my first tutorial so let me know what you think and I would love to see pictures of any you make.