Objectively speaking, making a masterwork mech was many times harder than making a masterwork crown.
The two product types were incomparable in terms of scale, complexity and resource investment.
The bigger and more difficult an object, the harder it was to make a masterwork out of it. That was the general rule.
This was also why masterwork starships and masterwork space stations were practically unheard of. While it was technically possible to make them, the fact that the CFA didn't even put any effort into making them was enough proof that it was too impractical to chase after these unicorns.
Then why did Ves possess a lot of confidence in his next two projects?
It was because he was a mech designer.