Now to cut the rabbets. The rabbet locations were all set out directly from the story-pole. The marks were placed on both sides and the marks joined with a straightedge rather than relying on a square to be square.
I planed the edge of a piece of scrap to act as a fence for my back-saw. I used a piece of material the same thickness as the cheek on the saw to space the fence out from the line. I could have also put the cheek on the other side of the saw so that the saw blade could run directly against the fence, but then you have issues with the teeth rubbing against the fence due to the kerf width. I also could have used a consistent thickness of material for the fence, and then made the cheek narrower so that it would ride on the top of the fence instead of on the surface of the material as a depth-stop. The benefit to running the blade directly against the fence is that you don't have to space the fence back to locate the cut. Regardless, this way works. I cut the first slot, then spaced over for the second slot, making sure to cut on the waste side both times.
I then used a chisel and mallet to remove most of the waste from the slot. After that I finished it with a router plane. I used the spear-point cutter for cross-grain work, even though it wasn't really that important since the rabbet was narrow and the sides were pre-cut.
At this point the rabbets are cut, but I still haven't cut this long piece of material into individual sides/top/bottom. This is because it's easier to hold a longer piece to the bench without having issues with clamps getting in the way of the router plane.
Next I will cut the sides, top and bottom from this material, and then cut the dovetails to join the sides, top and bottom together.