It is really quite simple. First you cut a long diagonal slice on the band saw. Then you turn the piece you have cut off OVER, and glue what use to be the top of that piece to the bottom of what was the top piece of the neck. After you have done that, it looks like this.
Then you draw straight lines representing the edges of the neck shape.
Then off you go to the band-saw again to cut along those lines.
And there you have it. A tenor neck blank all ready to carve into a neck once it has had a couple of months to acclimate in the workshop.
These four nice Spanish Cedar neck blanks came out of a 2 by 6 1/2 just 23 inches long.