First on my list, a thing I use very very frequently - Spawn a wire door and put it where you want it. Hook it up to a bunch of AND gates with buttons and have 4 to 5 buttons so 4 or 5 people are needed to get into your house (or knowledge of the Wire User, but nobody seems to have that)
Second, not sure how to do this myself, but I’ve seen it done. A prop is used to wall of the area and is turned into a fading door. There is a tube next to it instructing people to drop money into the tube and when it has X amount in it the door opens. I loved that one. (Before you ask, you have to put a nocollide-all’d prop inside the tube so that people can’t pull the money out once it drops through the prop.)
Post any of your ideas or things you have seen done.