They did have access to a fantastically good precision tool: humans with lots of time to learn and perfect their craft.
A important factor here is that the quantity of these things needed at the time was extremely low, compared to the length of their useful life after being made (and time taken to create).
A intricate castle or palace might take a hundred skilled people 30 years to make, but then it would stand like that for the next 700 years – needing only repairs and maintenance.
Similar with armor. A skilled blacksmith might need a few months to make a good suit of armour. That suit will probably stay in service for decades from then, unless the knight in question was flattened by a trebuchet projectile.
Latest Answers