I wanted to share my mistake to help others avoid making it....
Well, if you want to do something right, do it twice:)!!!!!
I did find the plan lay out a bit confusing, even though I read it several times.
I essentially cut out the spine piece wrong, which made the spine to high, and the x brace pieces were lining up exactly 12mm to low. There were 3 ways to fix this, the simplest, cut 12mm off the bottom of the spine section,or build a new ring and raise everything up 12mm, or make a new mold.
I actually built a new ring, and raised everything up 12mm, but after looking at the mold, I just wasn't satisfied
even though I could have made it work.
The best thing about this mistake is that I discovered MDF, what great stuff very easy to work, it will make great mold material in the future for other instruments.
Sorry here are the revised pictures, the latest and greatest mold , along with the old square up your sander pics, then the last two shots show the fundemental error in the first mold, and the second plan view ring glued on to raise everything up 12mm.
So if your looking at this gettin ready to build your mold, I would use the 1/2" MDF to build the mold, it is the easiest to work .
And double check the spine view and the plan view, aspects the plan.
HERE IS THE PICTURE OF THE WRONG SPINE CUT, AND THEN THE FIX.