Today I worked on the second flap drive pivot block. I had previously cut out the 1 inch wide strip from the 3/4 inch phenolic sheet. I trimmed the strip create two pieces 2-1/4 inches long and then worked at drilling the 3/16 inch holes. I used the flap drive mounts to ensure the alignment of the holes in the phenolic matched the aluminum mounts. I ended up creating a set of left and right flap drive blocks and mount. The final step was to use a spade bit in the drill press to drill the 1 inch hole. The holes seem to be a good slip fit on an 18mm socket that measures 1 inch diameter on the outside. I expect the production flap drive tube will have some paint on it that will require me to open up the flap drive blocks a bit. I plan to skip vent door latch but I still need to make 1/8 inch thick spacer plates.