I had a rummage around my fabric bags and came across some denim that was left over when I cut two pairs of jeans into shorts - a grey leopard print, and a black denim (slightly washed looking). As they were the lower parts of the leg, there was not a huge amount of depth to the sections of fabric I could salvage - I squared it off, and sewed the denim together, alternating between print and plain fabric. I then sewed the seams flat and I had a nice big piece of material to work with.
For the lining I used the bottom part of a black maxi skirt that I cut into a mini (just goes to show that you should never throw out fabric remnants!) It wasn't really cushy enough for a laptop sleeve, so I also added a layer of sweatshirt material to the lining (positioned between the two fabrics).
I had a hunt around the internet for a good idea for the sleeve - I toyed with the idea of doing a simple slip-inside pouch style, then thought I would challenge myself a bit more and make one with a zip. I had a 55cm grey zip that was the perfect length for this 13" notebook.
Now I thought there was no point giving you a step-by-step on the project, when this woman has done such a good job already! Here is the tutorial I followed: http://www.designsponge.com/2011/09/sewing-101-electronics-sleeve.html