As a body man with 30 yrs experience I can tell you all about it. None of these fillers have structural strength so NEVER use them as a replacement for welding. On the other hand when they are used for cosmetic repairs they are perfect. The ones with resin and hardener are what you want, and for...
your a frankengunner.......just one shot will knock the world off it's axis, I heard it on the net P.S. I cant wait to shoot it side by side with mine to see how much smoother yours will be (being that yours is based on a new design and mine is a 100 year old design )