Yes you could use silicone only. It is not terribly easy to form. it is either going to be a drop like a candy kiss or a bead. You can smooth it slightly as you are applying but it can turn into a mess. You might want to practice and experiment some first.
Silicone stays pliable, very resilient and quite strong for several years.
You can also buy black silicone but it is a little glossy.
If you use silicone only, I would let it completely set up 24-48 hours and then trim it with a new #11 (fine sharp point) Exacto blade.
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