I've started knocking a few idea around for a 4 string headless. I've got a an old Hohner B2A that I bought many moons ago when I was just a lad. It fell out the back of the guitarists Mini about 25 years ago and the body split, so I cut the sides off and glued on some 'wings'. It's a bloody mess but I've always quite liked headless basses!! So when some headless necks were for sale on here a while ago, I bought one and put it to one side for a project and now I'm looking at what to do with it.
The neck is really nice - just something about it feels 'right'. The tricky bit will be cutting the neck pocket for this as all three side of the heel taper from top to bottom (presume this was to aid removal from the mould) so this will need some thought. I will try to make some form of jig so I can use a router but it may end up having to be done very carefully with a chisel...but that's a long way off at the moment.
I've roughed out a shape and am thinking of using a pair of EMG pickups (a P and an MM) and a two band preamp. I've made a bass with an EMG MM and 2 band preamp before and really liked the sound of it. I've got one of the 'TW' versions for this so I can split the coil and so should be able to get P, P+J, P+MM and MM options from this setup.
This is my starting point but certainly not set in stone:
I have made a couple of basses recently with spalted beech tops so I will probably find something else just for a change!!