For those struggling with indicator lights: 1. Place several regular info_overlays with the material, "indicator_lights_wall" (make sure you pick the blue ones!) on the ground or wall or ceiling, just until you have a nice line from your button to your output. 2. Shift+click+drag all of your new overlays a space away or so, and then place the new overlays right back where the originals are. Then change the entity type from "info_overlay" to "info_overlay_accessor". Name them all the same name. (eg. "button_01_indicator_lights") EDIT: Name your info_overlays AND your info_overlay_accessors all the same name, just to avoid potential problems. 3. Create a env_texturetoggle and name it. (eg. "button_01_indicator_lights_change") Change the target brush to the name of your info_overlay_accessors. ("button_01_indicator_lights") 4. Go add an output on your button, or whatever triggering device you want to use, and name it "OnPressed", target your env_texturetoggle with the input "SetTextureIndex" and add a parameter of 1. Then add another output named "OnUnpressed" and target your env_texturetoggle with "SetTextureIndex" again, and add a parameter of 0. (1=On, 0=Off) 5. You're done! Stand back in amazement as your blue indicator lights become orange at the press of a button. You can also add the tick marks and the fancy Aperture icons (in the texture browser, type "indicator_lights"), and they work the same way. Just name them and add them to the target brushes key on the env_texturetoggle. (Separate multiple brushes with spaces) EDIT: Also, make sure that you name every separate line of overlays a different name so that one button doesn't activate all of your indicator lights.