So now you've got a stick and a blade. Cut the end of the stick so it tapers down on one side to the end like a wedge.
The handle for this particular paddle is a broken hockey stick from the rink at Kihei, Maui. I know from growing up in Minnesota that a hockey stick is the most suitable shape for grasping. I don't know why I've never seen canoe paddles with rectangular shafts. It works and feels great.
This blade is 8.5" x 18", which is big like a snow shovel. Later I cut it down into a smaller more graceful shape. Unfortunately I lost it shortly after taking that second photo. Take a sharpie marker or laser and write a return address on all your gear.