How hard is that stuff to sand? Do you think it would crack if you used it to fill seams? Like between the quarter extensions and quarter panel.
I have used the panel adhesive stuff. I wouldn't recommend using it anywhere that you have to use body filler or paint. I have found that the stuff shrinks and expands and can you can see where it has been used because of it. It would be great, for example, on putting on a quarter panel if used where the quarter normally gets spot welded to inside the door, inside the trunk, and where the bottom of the quarter joins with the trunk floor extension, etc. Then, all you would have to do is weld where it joins the roof pillar.
I agree with Craig. This stuff isn't meant to be exposed...it's strictly an adhesive. I think it would cause problems down the road if you tried to fill a seam with it like you're talking about.