Anyway, I did want some protection for it if I took it with me to visit Mom, for example, so I decided to buy some double-faced pre-quilted fabric and make a case. The outside is blue paisley on a chocolate brown background. There is a zipper pocket on the front for the power supply and external mouse (if anyone out there under the age of thirty can use those built-in pointer pads, I am surprised.). The outside pocket has a pleated bottom to hold larger items.
The case is made of a double thickness of the quilted material. I used the reverse side, a patchwork print in blue and brown, for the lining. The handles are inserted between the outside and lining and bar-tacked down the side of the case for strength. I made a shoulder strap to sew onto the sides of the case below the ends of the zipper, but have not decided whether I need it or not. If I had been thinking, I would have attached loops with D rings in the side panel so that I could attach and detach the shoulder strap as needed, but the case was already assembled before the idea came to me and I wasn't about to rip into the side seams to add the D rings. If I decide I need a shoulder strap, I can sew it on later.
I didn't have a pattern for this, just cut out freezer paper shapes for the body of the case and pocket, and messed around with the pocket shape until the pleated bottom came out right.