So I have a suggestion. This feature I used it in a very old server I used to play in before minecraft went "Official" (it was still Beta).I was thinking Aikar, Justin or any other coder in the team could make a plugin that would turn a player made structure into a chair. like putting wooden stair on the ground and 2 signs on the side would make the item possible to sit on. it would look something like this: Also it can be made like this: As long as the End connection block carried a Sign it would turn all Stair blocks connected in between both sings into an object your Avatar could sit on. that is how the plugin on that server worked. Of course that was only done with wooden Stairs, but I bet Aikar, Justin or any other coder in the team could make it possible for the other kind of stairs to have the same function.