func_plat

Very simple elevator that is easy to make.

1.Firstly, create a good sized room (300x300x300) and place your info_player_start and a light in there.

2.Make a walkway about halfway up the wall of your room.

3.Create a brush that will be your platform, and make it so the top face of it is even with the top face of your walkway. Apply the func_plat entity to your brush. You will need to set the "height" to the appropriate value, which is from the bottom of the plat brush to the top of the floor it will rest on in its lowest position.

4.Compile your map and check out your platform.

Here's a sample map showing this example.

Also see func_door for another variation on platforms.