Just hook it up at 2 (or more points)
Look at it and press Interact to hook on to it.
Could have as use a guideline to walk across slippery small paths while you work on your build for example and don’t fall the entire distance down again.
Or as zip line just slide down on it. Just a thought.
Zip lines!
YES!!
YES!!
Just saying the amount of times i have slipped of chiseling this alone
Would be cool to have zip lines going down from it after im done ^^
Oh god yes.
Would also be an alternative to adding minecarts or elevators and such.
Even to portals!!
I mean, I have a portal at my place that allows people to cross like 15 plots down, but you could totally do it with a zipline. 
It would also be really nice if only the two end-points of the zip lines had to be in beacons, and the actual “line” could exist in the wild without regenerating! Then, you could have zip line stations across long distances from two separate beacons where you wouldn’t have to plot the entire distance between them like you have to do with roads!
Edit:
Zipline recipe:
Iron Bar
Hard Coal (or Charcoal)
Zipline Pulley recipe:
Iron Bar
Titanium Alloy
Ancient Tech Device
(the recipe doesn’t actually matter right now)
Now, if we /had/ ziplines, there would be two ways to set them up.
Either
1.) Click on point 1, and it attaches, then a line of light follows you sort of like a grapple, and each block you traverse farther consumes another “zipline” item from your inventory, while getting closer returns it. Then, when you are at your destination, you click on it and they directly connect.
OR
2.) There are different ziplines that can be crafted with pre-determined lengths (let’s say 50 meters, 200 meters, and 1,000 meters). The numbers don’t matter right now, and there could be more than three kinds. But then you attach them to the two blocks across whatever distance you need, but you make sure that you have the right length of zipline in your inventory before you do.
Option 2 would make the most sense to me.
I kind of am in love with this idea now, but I worry it could never make it into the game. :’(
Maybe it will all we can do is hope for it 
This could be our new road system!
Hook up to it and it takes you flying down the line.
This would be a very progressive Boundless variation of the Minecraft railroad system. But I doubt it’ll happen. The devs may just suggest you use two grapples - attach one here, attach the other there and presto! You made a zip line!
