Rigidbodies, rigidbodies everywhere!
My first screenshot of developing in Unity (2014). Each piece is a rigid body with a constraint on each of the smaller pieces. Que the floating point errors and constraint conflicts! The CPU load on this was surprisingly high and I also learnt a valuable lesson about scaling physics to the engine. I work on the rule of thumb that one mass unit in Unity is 1 ton (assuming it's a 1x1x1 meter object). I don't want to get into specifics though for game play, whatever works and feels right.