So I started with two bath towels and a matching hand towel. (And for the record, apparently I wasn't paying enough attention and bought bath sheets when they were on sale - because these new hooded towels are huge!)
1. I laid both bath towels (one at a time) on my rotary cutting mat, wrong side up, and cut the left edge off one and the right edge off the other (long edges, mind you). I also cut the top (short) edge off both of them. I then put the two towels right sides together and sewed the long cut edges together. Then I serged the seam allowances and stitched them down to one side.
2. I cut the hand towel so that it was about 12 inches wide, leaving the bound (long) edge on one side intact. Then I cut the top and bottom (short) edges off. Next, I folded the towel right sides together and sewed along the long cut edge, eyeballing a gentle curve up to the fold. (The picture below shows the finished hood right side out and attached to the towel. You can see that it's about 11 inches long after seam allowances.) Like with the main towel, I serged the seam allowances and stitched them down to one side - I did pay attention and stitch them to the opposite side as the towel.
3. Next I joined the two pieces together: I pinned the center seam of the hood to the center seam of the towel, wrong sides together. Then I pinned the hood in both directions. I stitched the hood down, then serged the entire edge of the towel, including the seam allowances at the join. I turned the serged edge down and stitched it in place.
4. Happy customer! You can see how much my tall Thing 1 (5 years old) swims in this new towel. Oh, well...it'll just last longer, right?
These don't take long to make up, and they are great baby shower gifts, too. I just bought a bunch of towels on clearance to make more (though I did buy smaller towels this time!).