I was thinking while playing my last save that a creative mode might be a useful game mode. We already have peaceful mode, but a creative mode would pretty much only involve building structures and having hearthlings build them. No requirements for food, no enemies or events of any kind. Just a few hearthlings to build, and perhaps a vendor you can summon with a stall that can sell you however many items you need at zero cost.
It would work kind of like the micro world devs use for testing. You would be able to build, create templates for your main game, and test if the structures are build-able.