partly assembled ESR meter board

Sometimes i need to check the ESR values for second-hand or fresh electrolutis capacitors. Although ESR meters are available, it’s hard for me to spend a lot of bucks on one of it. So: the schematics is from, the case is from local supplier (a low-cost analog multimeter from China).
OpAmp, resistors and SMD capacitors are mounted. Black stripes at the bottom are milimeter marks on the metal ruler.