
I work from home and my organization gave me a laptop to use. I go back to our office in DC pretty regularly and up until now I've been using a huge, ugly backpack with a built-in laptop sleeve to cart my computer around. The backpack was free, and it's ugly and big and uncomfortable. I'm going back to DC this week for a few days, and I'll be traveling frequently for work, and I'm also going to DC for a wedding, so I don't want to carry around any extra baggage, so to speak! So, I finally broke down and made a laptop sleeve!
I don't have a pattern; I didn't even use any measuring tape, ruler or straight edge. I just eyeballed everything. I'm sure you can make it much more legitimate with a ruler! I had some scraps of neoprene in my stash that I got in the remnant pile at Joanne's, and some Amy Butler scraps for the cover. The neoprene has a black squishy side and a grey foamy side. The grey side is the "wrong side."
To measure, I laid my computer down on the fabric. For the width, I added about 2 inches on either side of the computer... the depth of the computer (how tall it is sitting on a desk) is about 1.3 to 1.5 inches tall, so 2 inches leaves enough for 2 seam allowances -- one to attached the cover fabric to the neoprene and another seam allowance to sew the front to the back.
Height -- fold over the fabric so it comes to just above the top of the computer, and then fold over the fabric for the flap and cut to where you want the top flap to end, plus 1/2 inch.
You'll see I sewed in a notch at the top flap. This is so the top flap will be flush with the width of the rest of the bag because we're adding the depth of the bag in with the width measurements. The width of the flap is just the width of the computer, plus 1 inch (2 x 1/2 inch seam allowance after sewing cover fabric to neoprene).
After cutting, place wrong sides together and pin cover fabric on top of neoprene and smooth out any wrinkles with your hand. Leave about 6 inches in the side to pull fabric through. Sew, trim seams and corners. Turn and iron.
Here it is turned.
Checking the measurements with my laptop. At this point, I sewed around the top flap to make a nice edge, just stopping at where the side "flaps" of the T start.
Sew on velcro. I only had skinny velcro on hand, so I doubled them up, and did a zig zag in between. Attached the velcro on with tape before sewing. To figure out where to put the velro, place your laptop on your fabric, and fold over the front piece and the top flap and see where a good spot is where they intercept to place the velcro. Mark with a pin, and before you sew your velcro on, center it width-wise on your fabric. Mine's a little off because I eyeballed it.
Then, sew vertically up the left and right sides of the fabric, lining up the bottom edge with the top of the T below the front flap.
Turn. Place your laptop in and smile!

If you want, you can see how the bottom edges are very triangle-y. You can box out the corners to make them look more sleek.
All in all, this project took me about 1.5 hours. Enjoy!!