Dennis-
I just use 30-minute epoxy. I add micro balloons continually, until it is difficult to get more in, not a very quantitative description, I know. A surprising amount of micro-balloon powder will be absorbed; so I continue to add it (sprinkling over the surface and stirring or folding it in as the slurry thickens), even after it appears that little more can be absorbed. The working life is limited, but has not been a problem. The consistency is VERY viscous. I don't use alcohol. The popsicle stick tool works OK without it, and smooths to the point that everything looks like a final surface. As the pictures show, though, even an even-appearing surface shows rises and valleys upon sanding. While setting, the fillets will flatten out some. So the sanding is necessary anyway. It smooths and re-contours a bit. The more micro-balloons, the easier the sanding. The picture shows what the stuff looks like after mixing and using some. I seem always to mix too much, because the volume grows with addition of the micro-balloons.