I've been using the 8" and the 16" dura block because it covers the whole dent.
image by -glhxturbo-
The 16" seems to flex a lot in the middle and dig into the dent sort of sticking up on the ends so I stopped using it.............but Im not sure. I was told to hold it in the middle and apply light pressure. I think I'll try to use the paper to create the contour for the flatter panel. It does have some contour to it.
I stopped using the flex block because it was too small and following the wave. That particular pattern has several different contours. The flex block has been good in some areas. Might have to get more creative
I'll put a skim coat on it and as soon as I see it break metal I'll stop there
Probably need to change the paper more often as well
I've also had problems with creasing the paper with the flexible blocks.