'Horizontal Sliding Door Prefab' is a small library and prefab set of horizontally sliding doors that I decided to make after having trouble with them in my own projects.

Includes:
slidingdoor_library.vmf: a library of four horizontally sliding doors: east/west, north/south, northwest/southeast and northeast/southwest. This file also includes the compass, a set of eight func_doors that move in their respective direction for easy reference.
slidingdoor prefabs: extract these to your prefabs folder for easy insertion into your map. These prefabs include a dev textured frame and the doors themselves are textured with props/metaldoor_01, but feel free to modify them to your own personal taste.

For easy installation, extract the contents of the ZIP file into the Steam\steamapps\common\Team Fortress 2 folder.