Its easy. First, it depends on the depth, clean the whole area.
Run a circle mask around insert. With a toothpick/safety pin/small brush, drop in a layer.
Not much, just enough to cover. Let Dry, it will dry to a thin layer
and level itself flat, even if you put a little too much.
Continue building self leveling layers until you can feel or gauge by peeling
back the mask, so it is close to level.
Based on the surrounding area of the insert, decide whether you want the last layer
as a fill, or with a larger mask, a feathered edge.
If you dont like the product, dampen a cloth, q-tip with Alcohol and remove it.
Taking 2-3 layers off takes no time.
Some jobs come out almost invisible, some you can see the last layer.
I have used it with mylar, touched up planking, coating metal posts, and parts in restoration,
hundreds of thousands of pieces of jewelry, shooter knobs, lock down bars....
Its a pretty cool product because it levels.
Whats bad about it.
Alcohol is the solvent, so chemically less durable, but not inside a game, unless you wipe down with
It can take more layers that an oil based filler, so a little more time, but it dries really fast.
Not as hard as a clear coat that is oil based.
But the stuff is pretty hard, and a common area of usage in coating is Brass handrails at Casinos,
(where I learned of it) This gives you an idea on its durability. I think the site has vids still.