Protecting PCB, multiplexers and MCU in vending machines

Hello everyone, I am working on a very low cost, small and basic vending machine ($300) with wooden cabinet for small neighborhood stores. As you may know, it is necessary to properly protect the components to prevent users from trying to steal money or damage the components. The PCB has a TFT display and several shift registers to communicate the ESP32 with the buttons, coin acceptor, bill acceptor, hopper sensor, etc. It's common for people to try to give any of these components a small electrical shock, and multiplexers are the most vulnerable. That is not my only problem, since the +5VDC and +12VDC power supply is not of very good quality, so I also need to protect/stabilize a bit the current that it supplies to the ESP32 and other components. So I'm looking for what low cost components I should use to protect everything or at least the essentials. For now it has only occurred to me to add some TVS diodes, electrolytic capacitors, some SMD capacitors and to protect against electrical shocks I don't know if I should implement a current limiter or Low-Dropout Linear Regulator or zener diode or some other component. I would greatly appreciate your suggestions. That is not my only problem, since the +5VDC and +12VDC power supply is not of very good quality, so I also need to protect/stabilize a bit the current that it supplies to the ESP32 and other components.

So I'm looking for what low cost components I should use to protect everything or at least the essentials. For now it has only occurred to me to add some electrolytic capacitors, some SMD capacitors and to protect against electrical shocks I don't know if I should implement a current limiter or Low-Dropout Linear Regulator or zener diode or some other component. I would greatly appreciate your suggestions. Regards.

reply »