"Can you provide more info on the wing root trailing edge fillets in your photos"
The leading portion of the wingroot fillets are modified Comanche leading edge fillets formed by pulling a mold off the Comanche fillets, then modifying the mold to fit a Cherokee (airfoil section is different).
The wing/fuselage fillets used a 3" or 4" diameter schedule 40 pvc pipe as a mold (I forget which). I used a hand winch to pull the pipe into a bow shaped curve that approximated the airfoil shape. The right hand side was modified by cutting out a triangular section to clear the baggage compartment door and then bonding that triangular section to the door itself. The dimension from the wing/fuselage intersection up to the top of the overall wing/fuselage fillet was chosen to just clear the bottom of the cabin door.
The trailing edge fillet was made in three parts - a top, bottom, and the inboard section that connects top and bottom.
The plug for the top was formed from a sheet of thin aluminum HVAC ducting cut into an oversized truncated trapezoidal shape which was then rolled into a truncated conical shape using balsa circular bulkheads superglued to hold it in place. Longitudinal skinny triangular wedges were cut out of the aluminum sheet with the edges pulled together and taped to form a 3D semi-conical top surface instead of a simple truncated cone. Assuring that the left and right sides were a mirror image was a bit of a chore. When I was happy with the plugs, I pulled the top molds from them.
A similar process was used to form the bottom plugs, providing clearance for flap deployment (including a provision for 2° of reflex on the flaps), and a match with the bottom profile of the fuselage.
The vertical plug for the top/bottom connector mold was just the aircraft fuselage with lots of painter's tape protecting it.
The planform trailing edge shape was cut from the assembled part partly from esthetics, but it was mostly controlled by the 3-D intersection of the curved top and bottom surfaces of the fillet.
The completed assembly makes a quite noticeable difference in performance at high angles of attack, but substantially less at cruise.
