https://www.airgunstocks.com/do-it-yourself/cold-bluing.html
Airgun Stocks: We duplicate gunstocks in your wood or ours from your master or ours. We specialize in fancy grades of Claro, Bastogne, and English walnut.
cold bluing
https://www.helixgunsmith.com/belgiumbluing
The Belgium Bluing process is a low temperature finish process that is used in mainly older firearms.
belgiumbluinghelixgunsmithing