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.

Weighted Companion Cube
The Weighted Storage 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 appears only in co-op gameplay. The cube is really a sphere, however, it still retains the colouring scheme and patterns present in the designs of the other cubes.

Discouragement Redirection Cube
The Discouragement Redirection Cube was introduced in Portal 2. Its main purpose is to redirect the Thermal Discouragement Beam (a beam of electricity) into other directions and portals.