How do I change Pivot point in MSPhyscics or accomplish this?

Extensions
2

I’m not clear on exactly what you want. Can you post another image which has two or three stages of the desired movement? For example:

  1. Fully closed
  2. half-way open
  3. fully open

I haven’t used MS Physics in about a year so I’m rusty on the details, but I think you can place a pivot joint at any location on an object. If you set the various objects to have collision enabled, then the movement of one object should interfere with its neighbors and cause them to move.