My game is a puzzle in a 3d world which the player needs to put some objects in a certain order as a pile. i was thinking about an idea that each time the player needs to bring the objects to a some sort of a portal and these objects will be teleported to the top of the pile and fall into their place, but it doesn’t match the concept of the game which supposed to be quite realistic… any ideas? 
This is realistic enough and dont require “teleports”, but it might look like the objects just pops in place. If you want to you could create animations aswell though.
Tag your objects and player with, object1, object2, player etc…
Create a trigger close to the area the pile should be.
Create a script that checks if a player is in it.
Then If there is a player in the trigger, check the tag of the object the player is holding.
Using a couple of if statements you can transform the position of the object according to the tag of the object.