This is his second experiment with epoxy, the first was a very small fill (also blue) in a knot on a board that is a cover piece for a gaming table he built--kind of like a craps table, there's an inner section that's lowered by about 4 inches and covered with cloth for dice, cards, what have you, then there are leaves that fit within the outer rails to make the surface flush for use as a traditional table. (But I can't post pictures of that until I get home again...)
It's not necessarily unforgiving, I think, unless you screw up.
There are different types with longer or shorter drying times, though, so you can start with a slower one and work your way up. The big thing is the swirls tend to settle over time, so if it's a slow one you have to go out there and stir it every hour until it's set.