Wow... that's a really good idea. But I don't want a wall... I want a bridge to become non solid. Well sort of. I want to make a laser that you can walk on. I have a func_wall as a clip brush and an env_beam going along the inside of the clip brush. Right now, I have the illusion that you are walking on the env_beam (laser), but I want to be able to turn the laser off, making whomever is walking on the laser to fall.
Is there no way to trigger a func_wall to become not solid?