Duane,

nice work, as always.

Just a thought, and it's mostly a cosmetic thing I know, but have you thought about thinning down the plug 1/8" or whatever all round for the last 3" at the loom end, so that when you wrap with the reinforcing cloth at the centre joint you end up with a constant diameter smooth finish rather than a fatter centre? Could taper the transition to avoid a stress concentration if required, and use a slightly tapered joining piece.

Since you were wondering how the commercial ones are made, I guess if you wanted the ultimate finish with a single piece of carbon along the entire blade you could build it like that to get a smooth finish, but with one less layer of carbon that usual, and laminate / vacuum bag a single full length layer of carbon along the whole paddle at the end...

dave.