– In the Collection Tab you can group objects. To make an object part of a Collection you can simply select it and then click on one of the 20 cells. In this picture you can see the 2nd cell selected:
– These collections are not the Scene Collections you can see in the Outliner!
– A rigid body interacts only with other rigid bodies sharing the same collection.
– Example 1: all rigid bodies belong to the same collection so they fully interact each others.
– Example 2: the blue objects belong to the 1st collection and the green ones to the 2nd collection. Note how the blue cube and sphere ( 1st collection) pass through the green board (2nd collection).