I decided to go ahead and make the door thresholds as my first project. I got a piece of 3/4in oak from the Home Depot Aerospace Supply Center and cut a form block in a similar style as the tail ribs. After some fiddling, I actually came up with a pretty decent part. I make the form block too short, but I decided to try anyway and with some patience it worked! Now all I have to do is make a mirror-image piece for the other side.
