With years of experience and my mastery in working with Unity's general functionalities, mobile and PC development, and C# programming, I am confident in my ability to not just meet, but exceed your expectations on this Unity PC setup project. My understanding of the unique requirements for interactive simulations will be an asset in handling your STL scene promptly and efficiently.
Furthermore, I am particularly adept at crafting intuitive user interfaces which would lend themselves very well to the selection of tools and adjustment of settings you require. I have also integrated VR capabilities into numerous simulations before, a feature that definitely holds promise in enhancing interactivity for your project. Of course, I'm no stranger to multi-user systems either - adding collaborative logins for the scene is right up my alley.
In similar projects, my focus on scalability and performance has always ensured efficient navigation controls, stable collision detection, and robust saving/loading mechanisms. Complementing these technical skills is my unwavering commitment to client satisfaction; I've always aimed to understand my clients' vision and bring it to life creatively without compromising functionality or visual aesthetic. Collaborating with me means ensuring a high-quality finished product that is both immersive and easy to use. Let's get started together!