Player 2 : Immediately turn to your right and get yourself up onto the ledge in the corner of the room. From here, look directly across the room and set a portal on both of the angled wall panels. Once all four portals are ready, hit the Arial Faith Plate behind you and you'll fly through the air towards the exit.
Player 1 : Pick up the Cube, drop it into the square bucket-like switch on the ground, then proceed back through the force field towards the entrance to the room.
Player 2 : From where you are, place your portals in the same wall panels where player 1's were previously. This'll create the same 4-portal pathway you used to reach the platform you're currently standing on.
Player 1 : Stand on the Faith Plate and you'll whizz through the portals and land beside player 2, allowing you both to proceed to the next half of the test.
Player 2 : Whilst player 1 is sailing through the air, you'll want to set a portal on the wall panel hanging down above the Arial Faith Plate and then on the vertical panel in the corner of the room to your immediate right.
Player 1 : Stand on the Faith Plate to send yourself backwards through the chamber, you'll - ideally - want to complete a full 'lap' of the room before player 2 hits the button.
Player 1 : If player 2 has timed their button push correctly, the Cube will be flinging its way straight at you just as you pass through the portal. Get ready to catch it with a deft press of the action button.
Player 1 : With the Cube still firmly in your grasp, stand on the Faith Plate that'll take you back to the exit. Drop the Cube in the red switch to open up the exit!
**** Missable Achievement/Trophy! ****
If you can catch the Companion Cube on your FIRST attempt (so it's down to player 2 to push that button at the right time), you'll be rewarded with the 'Iron First' accolade as soon as you get the Cube safely into its resting place near the exit.
Never lose a cube in Chamber 6 of the Mass and Velocity co-op course