Mentioned on John Sexton's Web Site - A Happy Day for Me
I suppose the flexibility of foam-core works to your advantage. In any case, this issue is not a widely reported one, perhaps it is a function of the working methods and materials. Also, it is faint, and not easily noticed...
By the way, I am over the moon, and very happy to see a lovely mention on John Sexton's web page. I noticed it today, and it has made my day! While I realise that I am beating my own drum, I hope others might share in my happiness. Have a look at this page, and scroll to the bottom, where my article got mentioned: http://www.johnsexton.com/workshop_endorsements.html