So in 3.5, there were some suggestions for assigning AC and hit points to common objects, but in 5e we're left to speculate - the PHB has precious little, and I didn't see anything in the DMG. DM fiat is great, but I'd feel more comfortable with some kind of starting point, at least.
The one thing I saw today is that the Wall of Stone spell gives each panel AC 15 and 30 HP/inch of thickness.
So, question: What baseline examples or techniques do you use to judge the "combat stats" of inanimate objects like AC, HP, and resistance?
As per usual, good answers will be from official or semi-official sources, or from personal experience of having used them in a game and seeing how they played out in a 5e context.