Moving multiple objects
I had an idea for a level design but have no clue how to implement it (easily), so I'm wondering if anyone else might know of a solution. How I could make multiple objects (i.e. a wall and indicator lights on that wall, several separate brushes, etc.) all move simultaneously without having to create a separate func_door or similar entity for each object? Kind of like how a button/switch opens a door, except all the objects would be moving in the same direction. Also, it doesn't have to be reversible, it can just be a one time event, but if a reversible solution exists, I'd definitely like to read that.
A func_door (like most other brush entities) can consist of multiple brushes. Just select all brushes you want to move and press ctrl + T. The individual brushes can be as far apart as you like, just make sure that the entity's origin (the purple dot) is located inside the level at compile time, or you will get a leak.
If you want some parts of the door to have a different function (e.g. indicator lights), you must create multiple entities that are attached to each other.
More info: http://developer.valvesoftware.com/wiki/Parent.
Note that the indicator light textures are overlays, which don't work on moving objects. To create moving indicator lights, you have to create new, non-overlay material files. This gets a bit technical, so I would recommend downloading a custom map from this site that uses moving indicator lights and re-use the .vmt files from there. One example is Hub, by Ald?z.
Other Portal 2 maps: Medusa Glare
Portal 1 maps: Try Anything Twice | Manic Mechanic