Here is a simple and affordable do-it-yourself project called the Envelope Laptop Case that requires no sewing at all. Just a few cuts and folds and you'll have your very own fashionable case for your laptop.
For starters, you are going to need a few supplies to make your own case: some fabric glue, scissors, pencil, ribbon (long enough to wrap around your laptop), a buckle, ruler, felt and canvas fabric. You can choose what kind of canvas fabric you like that best fits your personality.
Then lay down the felt, outline your laptop size and trace out the envelope outline with the ruler. Cut out the felt fabric and glue it to your canvas, fold down the edges and then fold the entire canvas around your laptop. Lastly, glue the ribbon on the back of the envelope and you are good to go.
Check out the DIY video as well for a better visual demonstration.