Thank you for your question! I purchased this with a series of clapperboards from an estate. I have 8 of them, all with varying material, color, and notations (letters and tape). Please feel free to check out the other items I have listed under my seller name too. I currently have an original production used clapperboard from "Firefox" that is ending tomorrow!
While I see the legitimacy in authenticating autographs, I am not concerned at all about listing this without a COA. This board is made out of perspex with etched lettering and has residual tape left from production use. I am absolutely confident based on the estate I purchased them from that they are authentic.
Also, I don't believe reproduction etched perspex "The Bridges of Madison County" clapperboards exist in the market.