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

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)