Hi guys,
I use auto body red putty, some say its to heavy. I sand 99 per cent of it off, real easy to work with, cheap, easy to find, doesn't ball up on you. I use it to fill low spots. Can use water to smooth, if you need to. It doesn't pull away and leave pot holes, when you sand it. I think Windy uses this product also, don't quote me but I believe he has made mention of it. Good luck and use what works best for you. Gary