Drawing Large Angles Using a Ruler, Yardstick or Tape
With your line ran between the two legs, mark eight inch or other chosen increments on it for the forty-five degree marks.
When marking degree points, mark critical positions, such as 90, 72, 60, 45, 30 and 22-1/2 degrees for easy location in the future.
Using this, you can mark any angle accurately. You can use a chalk line to mark the angle, if desired.
I'd like to see how others do it.
The reason I have what you want is, I never lent it out before.
Scraps are a myth.