Interesting build, the authors built a safe cracker that basically brute forces the safe by running thru a bunch of combinations. My 2 cents, would be good to add a feedback loop into it so it could hear the “click” of the pin to shorten the time up (could take 4 days to crack the safe). However if you get a safe at auction and don’t know the combo, this maybe a good solution.
http://www.theregister.co.uk/2014/10/13/heistmeisters_crack_cost_of_safecrackers_with_150_widget