Portal Test Chamber 19

This is the final Test Chamber and twentieth level of the game. It features the Unstationary Scaffold and High Energy Pellets, and Goo is present as the primary hazard.

Hazards

 * High Energy Pellets
 * Goo

Walkthrough
{{Spoiler|block=yes|
 * 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 through 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.

Alternative Solutions
It is possible to get to the cake without using the Unstationary Scaffold.
 * As soon as you enter this chamber, ignore the High Energy Pellet and fire a portal behind that blocking panel.
 * Enter the portal to the small safety platform.
 * Shoot the portal that leads to the switch and enter it.
 * Press the switch and quickly shoot the portal on the wall far behind the door.
 * Get a little bit through the portal, launch a portal far in the wall and quickly back up.
 * Do this again by shooting portal at the wall near the Goo that lead to the Incinerator/Cake.

(According to Partygoer Achievement/Trophy Guide video)}}