The "straight edge" is probably 1/2 of a pair of winding sticks.
Winding sticks (usually one light and the other dark wood) are what you put on each end of a plank of wood and then eyeball how parallel they are.
For taking out twist.
You eyeball them, then plane the plank, and eyeball the sticks again, and so forth.
You can get pretty true this way.
Unless you have a --real wide-- power joiner and a very steady hand, its still the only way to save a wide beautiful piece of wood.
I still don't know where to get this "magic" stain. I have a lot of quilted and curly madrone wood. A kind of wood you seldom ever see figured.
I am finding it very difficult to bring out the figure though
yours Scott