The Final Product!
Now that the protective sleeve is fully completed, all you need to do is place it in the bag. I added additional padding in the form of bubble wrap sheets to provide some protection. Not for the lens, but for the camera body. The lens is already well-protected.
Here is how it looks like with the Nikon D70 camera and its kit lens inserted. The bag close easily enough and the second picture shows what it looks like with the bag closed.
Now, I can carry this small backpack wherever I go, without worrying about dropping it. Of course, I'm not going to drop it just for the heck of it! But it's certainly comforting to know that it's being protected by a rigid sleeve.