Companies like Tekton don't have in-house designs, they pick up whatever they can get some suppliers around the world by first starting with an opening bid. Germany, Japan, USA, China, Taiwan are common go-to's for Tekton. Quality is quickly becoming a moot point now unless we are buying old stock from decades ago.
Picard makes very nice hammers.
Grobet used Picard as the manufacturer for their metalsmithing/metalforming hammers for decades, and hand forming for metalsmithing requires a lot of hammering, and the user wants a perfectly balanced hammer. The Picard hammers were wonderful.
The hammers for metalsmithing/metalforming from MOB-Peddinghaus that are made in France are nice, but not as nice as the the Picard hammers from what I’ve seen.
As far as I’m aware, neither Martin or Vaughan made hammers that covered the types Picard and MOB made for metalsmithing.
Martin does manufacture auto body hammers, and those are usually sold in the USA, instead of imports from Germany of Picard hammers, who makes similar auto body hammers, or maybe MOB.
I’m not sure whether the auto body hammers from Picard are made to the same standards as the metalsmithing hammers from Picard.