Step 1: Basic Shape and Cutting the Rabbets
I used a belt sander to shape the basic profile. Working with the grain of the walnut, which runs along the prongs for strength, I shaped the profile you can see.
Then I used the table saw to cut the rabbets. This was tricky and I messed it up a few times. I ran the piece through on end with the saw very close to the fence. The problem I faced was that the cutout for the saw blade was too big and the piece wanted to fall down. That made the cut inaccurate as I was basically free handing it. Next time I'd use a sacrificial board with the blade raised through it but I couldn't see a way to fix that down at Techshop, where I was working.
Step 2: Cutting the Prongs
Since I wanted the prongs to be as closely spaced as possible, I got one of the staffers to change the saw blade for a laminate cutting blade, which has a finer kerf.
Since the profile of the comb was rounded, it tended to rock as I was making the cut. It might have been better to wait until after cutting the prongs to do the shaping. My thinking was that the prongs might be damaged by the shaping process but, in hindsight, I don't think that would have been a problem.
I was mainly working by eye for the whole project and I realised that the rabbets were too small after I cut the prongs. I went back and carefully recut them to be longer afterwards.
Step 3: Glue Up
Step 4: Final Shaping
I had intended to add some dowels in the corners as in NoCleverNickname's original design but I ran out of time today. I think I'll go back and do that later.