Ability to merge objects

Hello! The ability to merge different objects into one should provide much flexibility and ease the work for many users.

What I mean by merge: imagine you're building a stairway to crypt. You've selected stairs, crypt you like, creatively misused them so they look really nice and unique (by stacking multiples of other objects), but then, you want to recreate it, make a copy or anything like that, to add it into another place. Well, now you have to do it all over again. Wouldn't it be nice to have a button that "merges" all the objects into one and then considers it one for further use (possibly revertable?).

Please see an example: https://www.youtube.com/watch?v=Lhol4uqh6OU