It would be better to get him and everyone else in the house to remember to shut cabinet doors after they've been used.

I'm going to take a slightly stronger stance and say "Don't get him something to fix this problem". We learn not to be careless by smacking into things. That's just how it goes. Some of us learn as children, unfortunately he can't do that. He still will. Good luck OP.

In my opinion the sensors are complicated and unnecessary because he's going to get used to his condition. My father is blind and he is great around the house, we don't leave cups and plates everywhere and we leave cabinets closed, and so does he, because otherwise he forgets where he put something or what cabinet is opened. He also makes us lunch every day so he is the proof that his condition isn't the end of the world. Soon you too are going to forget about it as a difficulty. Good luck, stay strong!

HI there are some elastics that can be used to close doors. This is not for the blind, anyone can use them. Other than that, remembering to close those things will be a good start.

Has he looked into getting a mini guide? They basically use sonar to tell you about stuff you might be walking into