The picture is conceptually like looking at the end of the core while channels are being glued into place.
I found an old photo that is better, my 1st cut and paste job,
crude especially at this stage, but the eventual result was pretty good.
Core profiled as usual, incisions cut with a pull saw freeing the channels, board attached to table, wedges and screws position the freed channels, goo glues it together. Remove, flip, repeat. Use tape and plastic to protect vs. epoxy spill/flash. White patch at left board corner shows what happens when the router sled is not aligned just right - that corner ended up too thin, so built it back up with epoxy bog.
Instead of so much bog along the channel edges on the deck side I could have glued in little strips of core wood and shaved them down for better cosmetics, but it was just an experiment, and I'd already had to bog the corner, oops, so didn't bother.