Paint will not stick to silicone caulk as mentioned above. Also, with a product like silicone, which stays flexible rather than hardening up, you will get dirt and grim building up on your fillets. Almost anything that touches that fillet will stick to it.
I imagine you could use painters caulk though. It wouldn't be any harder to work with that epoxy. It would make a much weaker bond between the fin and body tube than any type of glue. I personally wouldn't do it because of that but I imagine that for most low power applications it might work.
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