Upgradeble Walls

[Haraldson]

Another great Idea will be Walls that i can upgrade so i dont have to remove all and build it new. For example: i have wood wall and want to upgrade it to steel . . . i mark the wood wall and click on upgrade and choose the material

[CannibarRechter]

Same with doors.

[Peng Qi]

Or even just a "replace" command would be nice.