I have been searching for the ultimate epoxy glass for years.

I might have found it today.
After the first epoxy glass coat I let it dry for a few days.
Sand it as usuall and mix up some more epoxy for the second coat.
Normally I would mix the two parts together and pour it on and slop it around
and scrape most of it off.

Today I tried a different appch.
I let the mixed epoxy sit in the cup for about 5/10 munutes first.
This lets it set up just a little and prevents runs.
I then dribble it on and scrape it off.
When it is a little more set up it flows MUCH BETTER and
runs MUCH LESS.
I would watch closely your mix cup and keep stirring untill it just starts to get a little "slower"
to drip off the mix stick.
Try it it really works for me.
Greg