Just so you know, un-thickened epoxy alone is not the best choice. That's because it's rather weak and brittle without any reinforcing (cloth, thickener). Here is what I would do:
1) If it is not hard yet, scoop out as much of the neat epoxy as you can, then add thickened epoxy. If it's not hard it's in the "green" stage and you will get a chemical bond between the two.
2) If it has completely hardened, I would drill it back out. Any neat epoxy remaining will not be a problem. Then paint on some neat epoxy, and thicken the rest of it and then fill the hole.
When the whole thing is at the green stage (rubbery but not sticky/wet), then use a chisel to make it flush with the surrounding surface. If there is a low spot, you can fill it again at this stage with no prep (later you would need to wash off blush, then sand, then clean).
You may have had a problem because you have a "blind" hole. This means there is no place for the air to go, and it's hard to get the epoxy in. There are a few things you can do:
a) Use a syringe, and fill from the bottom of the hole, withdrawing the syringe as you go.
b) or poke at it with a paper clip or something as it is curing, so the air bubbles up and out and you can re-fill.
c) again, if it slumps too low as air is released, re-fill it to a hump, then slice off said hump with a chisel in the green stage (soft/rubbery but not sticky/wet).
Sunbeam
1) If it is not hard yet, scoop out as much of the neat epoxy as you can, then add thickened epoxy. If it's not hard it's in the "green" stage and you will get a chemical bond between the two.
2) If it has completely hardened, I would drill it back out. Any neat epoxy remaining will not be a problem. Then paint on some neat epoxy, and thicken the rest of it and then fill the hole.
When the whole thing is at the green stage (rubbery but not sticky/wet), then use a chisel to make it flush with the surrounding surface. If there is a low spot, you can fill it again at this stage with no prep (later you would need to wash off blush, then sand, then clean).
You may have had a problem because you have a "blind" hole. This means there is no place for the air to go, and it's hard to get the epoxy in. There are a few things you can do:
a) Use a syringe, and fill from the bottom of the hole, withdrawing the syringe as you go.
b) or poke at it with a paper clip or something as it is curing, so the air bubbles up and out and you can re-fill.
c) again, if it slumps too low as air is released, re-fill it to a hump, then slice off said hump with a chisel in the green stage (soft/rubbery but not sticky/wet).
Sunbeam