Symmetry Mode in Survival
As the title states, I'm suggesting Symmetry Mode in Survival. I tried searching for other similar topics before I posted but couldn't find any, so I'm making my idea suggestion now.
My idea for Symmetry Mode in Survival is, you have to craft a 'drone' that is essentially an item you keep in your inventory that allows you to you use Symmetry Mode while in survival.Now obviously, since it's Survival Mode, the blocks won't be placed already built like they are in Creative Mode, but instead would just be the base of block as if you placed it normally in Survival. You would also need to have the materials available in your inventory for it to work.
The reason why I called it a 'drone' is, the idea is that you are building a mini 'drone' that will place the other symmetrical blocks for you. However, there wouldn't be an actual flying drone, that would just be the basis of the item. It would be just like the Oxygen and Hydrogen bottles you keep in your inventory that refills your suit even though you don't actually need to hold the item and manually refill your suit, it just does it automatically. So this 'drone' would be the same thing. As long as you have it in your inventory, and you have supplies for the blocks, you can use Symmetry Mode in Survival.