I'm helping to build a game using the Unreal engine. My friends are working on other parts of the game such as UI, AI, npcs, camera and movement interpolation, etc.
My job is to work out the building system for the game. I want to be clear that this game will be a sandbox game like Garry's Mod or Minecraft, but that is overshadowed by its role as a 3D modelling software that is meant to replace the combined forces of Civillo, Civil 3D & Revit. I want the building system to be extremely advanced, but also extremely intuitive, because the player doesn't pan or rotate around objects, rather they move around and look at them. The building system will be based off control lines, and the schematics that can be swept across those control lines can be customized within the game. I also want the world file to save as a dwg file + a player data file. What do I need to know to allow players to edit assets from within a game in the unreal engine?
I don't want them to upload assets that are otherwise modeled in blender or use any API's which depend on existing 3D modelling software because that would rather defeat the point.