Make a reversible laptop sleeve with Instructables' easy to implement tutorial.
This is pretty basic sewing and can be completed in under an hour (not counting your trip to the fabric store to dither over all the cool fabrics, however). Note: laptop sleeves are meant to cradle your machine when they are in sleep mode or completely off; otherwise, you run the risk of overheating.
How to Make a Reversible Laptop Sleeve [Instructables]