A one peice all carbon bar, captain seatpost, and stoker stem would be real easy if all the dimensions were finalized.

Carbon post, carbon bar and a short length of carbon tubing. Miter the tube to the proper angle and radius, plus length. Tack it together to verify, then wrap it like a Calfee.

Doing this in aluminum is not a smart idea unless you can accomplish heat treating the aluminum after welding.

PK