Here is the start of the neck. It's made from maple, and is formed from a central core and some 'wings' glued on. The recessed section underneath where the fretboard will sit is to accomodate an extension of the belly. I noticed this feature in the mandolin I took to pieces and I presume that it will add strength to the neck - body joint.
I have been wondering whether to glue it on to the bowl and then do the shaping, or shape it first - I will probably go for the first option.