Paint cube with propulsion gel. Bringing along the cube, walk and jump over light bridge to the ledge.
Drop painted cube on top of light bridge. It will start to slide down, deactivating the laser fields one by one. Run through the deactivating fields.
Stand on button, create a portal connection to where you just came from below. Portal down, get a cube, portal back up.
Use portals to cover floor with repulsion gel. Use same portals to bounce, fling and bounce over the chasm, bringing the cube along. Place cube on button.
The track played during this chamber is called Obscuration, which can also be found in Portal: Stories VR, a VR game which was made by many of the same people.
