This has probably been suggested before as freebuild or creative but I think it would be handy if there was a main menu option for “template mode”.
In template mode you cannot do quests, you do not get attacked and it is just a flat surface to build on with a bunch of hearthlings and never ending resources.
The idea being that you design your template and simulate the building process to ensure that the template can in fact be built by the AI.
The hearthlings would build said buildings at the rate of a tier 3 town this would allow players to design templates outside of single player and multiplayer and also ensure the templates do in fact work.
I am not talking a true creative mode more of a simulated building mode.