Cubes

Cubes are common gameplay implements in both Portal and Portal 2.

Weighted Storage Cube
The Weighted Storage Cube was introduced in Portal and remains prevalent in Portal 2. In Portal 2, the blue ring turns yellow when placed upon a Heavy Duty Super-Colliding Super Button.

Weighted Companion Cube
The Weighted Companion Cube was introduced in Portal and remains prevalent in Portal 2. Something here about how Valve wanted players to feel attached to the cube, and realise that they had to keep the same cube throughout that entire chapter in Portal.

Edgeless Safety Cube
The Edgeless Safety Cube was introduced in Portal 2 and is used only in co-op gameplay. It only appears once in singleplayer as garbage. The "cube" is really a sphere; however, it still retains the coloring scheme and patterns present in the designs of the other cubes.

Discouragement Redirection Cube
The Discouragement Redirection Cube was introduced in Portal 2. It's main purpose is to redirect the Thermal Discouragement Beam (a deadly and harmful laser) to other directions and through portals if necessary.

Weighted Storage Cube Receptacle
Weighted Storage Cube Receptacle is a receptacle for the Weighted Storage Cube, introduced in Portal 2. The Storage Cube must be placed securely inside the receptacle for the player to move on. Although its appearance is similar to the Heavy Duty Super-Colliding Super Button, it cannot be activated by the player or any other object being placed on top of it.

Edgeless Safety Cube Receptacle
The Edgeless Safety Cube Receptacle is a receptacle for the Edgeless Safety Cube, introduced in Portal 2. The Cube must be placed securely inside the receptacle for the player to move on.

The Edgeless Safety Cube and its receptacle only appear as gameplay implements in co-op mode.