Often referred to as the "Four-Way Door", this is a combination of the Star Trek Door and the Split Door. It's very decorative, despite its simplicity in construction.
Construct a Star Trek Door, but replace the sector tag [0,9] with [0,26].
Raise the floor and lower the ceiling of the door until they meet in the middle. The Star Trek Door texture will be covered by the default brown brick texture. Replace it with a texture of your choice. As with the Split Door, the texture will be flipped incorrectly. To fix it, point the mouse cursor at the top half of the door and press 2. Now you can edit the two halves separately. You can paste the texture to both halves of the door and use the F key to flip them around.
Now the door will be functional in the game. The door opens as shown below.
Notes:
- The door's sound effect will play more than once. Check the "References - Sector/Effector Tags" section for more information about this.
- If you trigger the door quickly and repeatedly, sometimes one set of doors will close while the other opens! This forces the player to run through the door in the split moment that both sets of doors are half-opened.