How to practice the development of large-scale systems?

Since not everyone has opportunities to do it at work, how to practice in playground projects if you don't have a cluster at home? I personally feel quite interested for the area, but have difficulties to keep studying only the theory. My current approach is to create a small project – with real data – design an architecture for specific constraints, and estimate how far it could go. Later, I start thinking what I would do to improve it to reach the next level.

I wonder if there are other or more effective ways of doing it. With this approach, I constantly see myself paying too much attention to implementation details and not really practicing concepts or tools too out of my comfort zone.