Wheatley (Portal 2)
This Portal 2 aesthetic theme is showcased in Chapter 8 and 9. It is characterized by either mass-scale destruction of the chamber, or regular clean themed. The walls are torn apart and you can see all sorts of things outside of the chamber: Gel pipes, other chambers, catwalks, and fire. Each test is monitored by Wheatley shown on a screen.
In-Depth
This is the last theme the player will encounter in the Portal 2 Single Player campaign. The large destruction of the chambers is mainly caused by Wheatley's terrible handling of the facility. A main part of the map is the outside area, which is seen through the gaps and tears of the test. You will see lots of things breaking, falling apart, and on fire.
Noticeable Elements
Excursion Funnel
Entity prop_tractor_beam is one of the main elements seen in the Wheatley chambers. It can be used to transport the player, objects, and gel, and can be transported through portals. Creating a whole for the funnel is necessary, or else it looks odd in the wall. If you want the funnel to start reversed, set 'Linear Force' to -250. For reversing it through a trigger/button, create the output:
My Output Target Entity Target Input Parameter Delay Only Once 
OnTrigger FunnelName SetLinearForce -250 0.00 No
Don't forget to add an extra output to reset the funnel. A number less than -250 or higher than 250 will cause the funnel to move faster, and lower numbers to have it move slower. It is recommended that you not change the speed of the funnel. The funnel turns out glitchly-looking. You should only use 250 and -250.
Gel - Gel was an element carried from the Underground themed maps into the Wheatley test chambers. You can still see lots of pipes crowding around the facility. Gel now comes out of regular cube droppers. In the PTI update, they have new Gel Dropper models. Create gel using an info_paint_sprayer.