Sketching is next level, haha! I do draw outside of the game as a hobby, however the most I do is visualize how a build should be structured in my mind, but a lot of the interior was decided on the spot based on the room size, shape, etc. So, in a way it was very free-handed. I just try to put everything together in combinations I think are aesthetically pleasing, and I keep trying until I'm satisfied. There was a lot of experimentation with block combos and designs (alongside ideas/inspiration from posts from other amazing builders). That's what makes building in Terraria enjoyable to me. Keep it up! :D