From the Portal Wiki
This is the twentieth and final Test Chamber in the game. It features the Unstationary Scaffold and High Energy Pellets, and Goo is present as the primary hazard.
- High Energy Pellets
- Walk to the end of the hallway. Shoot portals on the tilted panels to get the Pellet to the catcher. If you didn't succeed, wait for the Pellet to be on the side of the catcher and then place the portal from under the emitter to the wall in front of you.
- Hurry on the Unstationary Scaffold and duck to get to the other side of the metal pipe.
- Jump on the platform on the corner and then get back on the Scaffold, when it is on the other side of the platform.
- Turn to face the switch and press it as soon as you can.
- Turn around and shoot a portal to the other side of the opened door.
- Fire the other portal on the wall near you and when the platform is in front of the other portal, go through the portal.
- Place a portal at the end of the hall near the ceiling. Put the other portal on the wall where the Pellet is bouncing off.
- Fire a portal on the wall ahead and the other portal on the wall on the left - behind the wall.
- Watch trhough the portal as the platform moves to the other side. Wait until you see half of the platform and then go through the portal on the same platform.
- Prepare yourself for the cake.
- in progress -
- There are rooms accessible in chamber 19 that are looking out over parts of test chambers 09 & 14
- The test chamber you end up in after riding the cube dispenser tube is Test Chamber 09.