Has anyone ever heard of a tool called Hammer Sandbox? I used it a little before it went away. What it does is it converts a prop for example and turns it into a block that is part of the map. Me and a few others used to build simple maps using it without the hammer editor. Here is a map by map change of me and a few other players constructing a map using the tool:
UPDATE: I’ve managed to emulate it’s functions and so far it is able to build brushes and basic lights. Hosting a closed beta test on it soon.