I believe this would be fairly easy to implement with a simple plugin, I could even program it though it would take a few weeks. Easily doable though, there may possibly be already something out there that could be used.
We do currently have elevator signs that can be created if you have purchased the engineer perk from the Travelling Wanderer. Those work similar, though are sign based rather than block based.
All you need to do to create one once you have the engineer perk is:
- Create a sign and place against a wall with [Elevator] on first line (remaining lines can have whatever you wish for reference purposes).
- Create a second sign directly below or above where you wish to travel to, with the same [Elevator] on the first line of sign.
- Continue to create as many elevators as you desire.
Usage: Simply crouch and right-click sign to go down, right-click to go up.