Two solutions that I have used.

First, a meter long industrial cable tie, which I would wrap around the safe after closing and locking it. The manner of installation and type of safe can make their use impossible, but you can use them on most hotel safes. Cheap, and easy to carry in your luggage.

Second, I now carry a PacSafe travel safe whenever I will be staying in hotels. Ballistic nylon bag with embedded wire mesh, and a hardened steel cable which wraps around an immovable object and then locks to the safe. I use a shrouded Masterlock instead of the less secure lock that comes with the PacSafe. A thief would need bolt cutters to be able to take the bag. PacSafe products are available at SuperSports stores in Thailand.

Neither system is foolproof, but will stop a casual thief.

I would not even put 200.000 THB in a safe. My watch is more expensive and I wear it every day. My camera equipment is more expensive and both stays some were in a hotel room. So don't worry about 200.000 THB in a real hotel.

Sent from my iPhone using Tapatalk

Absolutely not, why would you?

Can you change the combo and make them impenetrable?

The best safe is a place where nobody expects to find money, like in a book and other objects hidden at the bottom of a bag.

This is a great tip. If you have no choice but to walk through a bad neighborhood, hide your cash and wallet in a disposable drink cup and when you get robbed it will be the last place the bad guy looks.

I would trust the room safes than just keeping all the things in the bag or open in the room. Instead of taking any chance, it is better to use the hotel room safes to store the valuable items as it minimizes the chances of thefts.