For laser trimmed resistors, there's always hand sorting resistors. Even today, that's how I've seen it done in commercial op-amp characterization. Tests like

For laser trimmed resistors, there's always hand sorting resistors. Even today, that's how I've seen it done in commercial op-amp characterization. Tests like CMRR (Common mode rejection ratio) require precisely matched input resistances or the result is thrown off by mismatches.