Attachments
Previously, when attaching parts together with a hinge, the game would attempt to remove any rigid attachments that would prevent these parts from rotating with respect to one another. Now that you can go in and delete individual attachments after the fact, I’ve removed this behaviour as it was somewhat arbitrary. At this point I think it’s better to leave it up to the player to decide which attachments to delete.
In conjunction with this, any hinges whose connected parts can’t rotate (due to being also rigidly attached in some way) are now highlighted red. This will hopefully help you debug stuff in your constructions that isn’t rotating as you want it to.
Physics collisions
Up ‘til now, subsections of constructions that were directly attached together with a hinge would not collide with each other. As of Unity 4.5, the PhysX flag that enables these collisions has been exposed, so I’ve now enabled it in game. No more parts passing through each other, woop!