All i did was update Conna's tools so they arent as buggy and so on. This is a must have in single player and in multi player!! This contains a fading door, fans, position switcher, ( great for teleporting) much more.
This download looks like an addon. You need to extract the downloaded zip and put the addon folder in your Garry's Mod addons folder. You should end up with a directory structure similar to below: