Since you mentioned smog/Thermactor bracket guess your asking about a 428CJ application especially considering your screen name. Since these are all added to the engine at the engine plant they all share the same details in this area.
Believe these were painted (the black semi-gloss brackets) by the providers.
From observation paint does not look very thick but has a nice full coverage so would reproduce by spraying. Originally the supplier may have used the electrostatic method of painting.
