Pictured here is the result of a couple of hours spent shaping the heel. This is as far as I'll proceed for the time being; I'll carve the neck and fine tune the shape of the heel after the fretboard has been glued to the neck shaft. I've chosen to rough carve the heel prior to attaching the radiused fretboard as it's easier to secure the neck in a vice or clamp it "heel up" to a benchtop without it.
I use a template to pencil in the shape of the heel where it will meet the sides and a second template to mark the outline of the heel cap. Although the intersection of the heel and the sides is critical to the accurate alignment of the neck with the centreline of the body and is crucial in establishing the correct neck angle relative to the bridge, there's a large degree of latitude where the shape of the heel itself is concerned. It's an ideal opportunity to inject some creativity and there are some wonderful examples where luthiers have done just that. Personally, I prefer to keep it simple and a graceful set of curves and a slim, refined look are my primary goals.
I carry out the initial shaping using a variety of chisels, then move to rasps and files. As the heel approaches its final shape I switch to scrapers and sandpaper. Shadows cast on the heel while holding the neck up to a bright light help identify any remaining lumps and bumps. Although I'm aiming for symmetry, I'm not obsessive about it - I'm happy to rely on visual cues such as this to highlight any inconsistencies.