Being a dog family that's usually busy with our weekly routines, there's not a lot of time we can take our dog for walks, so we usually would end up having to let her outside on a leash. Our backyard woods is plenty big enough, but since its mostly forest its difficult leashing the dog to one tree as she'll get tangled or end up in some other treacherous situation when she tries the simple act of walking around. What we realized is that dog leashes can be problematic based on the fact they're usually tied to 1 point of axis, and the radius allowed from the length of the leash can be obstructed from obstacles within the radius of the leash. Dogs are animals that usually like to roam and explore even, and we wanted to provide a outdoor experience for our dog that can meet the demand of exploration as well as fix the issues most leashes have.

I present to you the Dog Zipline

Taking heavy influence from human-accessible ziplines, the dog zipline is an easy solution to a lot of issues dog owners may face; it presents a multitude of benefits to you as well as your canine friend. The zipline will consist of a rope or bungee loosely hung between two trees or walls high above the ground (try to put it up as high as possible to avoid walking into it), with another rope or bungee clipped one end to the zipline and the other end on your pupper's collar to serve as the leash. This simple to create device can add so much more versatility to your dogs daily time outside, especially if you have a large backyard, don't have fenced in land, or both!

Here's some benefits to making a dog zipline of your very own:

The main feature of this structure is that it will allow the dog to pull itself back and forth down the length of the zipline, along with the available radius made from the length of the leash, making almost a "hallway" of space they can reach too.
Having the leash's end in the air connected to the zipline really cuts down the chances of getting tangled, the leash itself will hang suspended at all times above the ground preventing objects from getting "swiped" by the leash. This will allow your dog to move freely as if someone was constantly walking them, holding the leash at a higher angle.
This amount of new space will allow opportunities for different dog activities: they could chase small animals that dare step into their zipline zone, you could utilize this long area to play long distance fetch(catch) with your pup while they're safely leashed, you could even go on small walks with your dog up and down the zipline without having to hold a leash yourself.
This can eliminate the need for multiple leash areas if you have multiple places outside you may want to keep your dog around; for example on the right side of my house is my sliding door from the garage where it's easiest to let my dog outside, this right side has a big shady tree and boulder she can rest under. Then on the other side of my house is the yard where we set up the pool and have campfires, and she can now run over there as she pleases.

*Disclaimer: If your dog has ongoing issues with attempting to run away from home, it may be best to train them a fair amount more before allowing them outside on their own, especially big dogs.

*Make sure your materials are environment and dog friendly, metal chains or jaded wires could cause quite a predicament if they tangle, especially near your precious animal.

*The dog zipline is not like a human zipline and likely can't support much weight, so I'd strongly advise not using it to suspend anything in the air, especially a living being.

Step 1: Materials

Make sure your dogs collar can safely attach to a leash in general
Rope or cable for the leash itself, make sure its able to be tied around a hoop or carabiner, with the other end able to attach to the collar. An actual dog leash with swivel clips can be a superior substitute for anything homemade.
Rubber or steel cable for the zipline, this can also be a dog leash as having clips at the end will make the process much easier.
Carabiner(s)
Two sturdy trees, or two sturdy walls or stationary objects you don't mind being drilled into
A powerdrill
Eyehook Screws (2)
You may need a ladder to reach your desired height for your zipline

Here's a product that supplements most of these requirements as its almost entirely prebuilt:

https://www.amazon.com/BV-Pet-Aerial-Trolley-Runner/dp/B01M6A1ATC

Step 2: Setting Up the Zipline

Installing the zipline should be a pretty quick process, determining where your's will be is in your hands. Just make sure your line is long enough with a few extra feet for slack. You want to start by drilling appropriate holes for your screws in each tree or surface, and then inserting the screws with their hooks. If your choice of line for the actual zipline comes with clips at both ends then you can easily clip onto the hook, and if not you can tie it around the hook or to a carabiner that can lock in. When drilling into your second hole, make sure you're as horizontally level as possible with the other hole, so your zipline is even as possible making it easy for your dog to pull along it.

Now before you tie up both ends of the zipline, slip your loop or carabiner around the rope that will serve as the pully, if you need to tie your leash to your pulley it may be easier to do that prior before pulling the zipline cable through. If you have the skill/ambition to do so, you can replace this step with a small wheel-pully system for cables.

Now after hanging both ends with the leash already slipped through, you've basically set up your zipline! You may have to adjust your height if you realize the screws weren't even with one another, or your cable may be too long. All that's next is hooking up the leash to your dog, and making sure their new expanded play place is safe for them to roam.

Step 3: Closing Statements

I hope you were able to set up your dog zipline to your liking, my intention of this tutorial was to provide a general sense of what this device could provide, and its totally up to you to modify the device or building process to meet your needs, especially since its your dog to be taken care of. I apologize for my pictures being somewhat hard to comprehend because of the snow, I live in New England and we just got our first taste of winter. Remember to always someway monitor your dog when they're outside alone and don't leave them out there for too long, they could wind up in some kind of danger outside or even just get bored. Although the zipline may make going outside more fun for dogs, they may desire being inside with the owners they love just that much more (Or inside could be better for a dog then outside, especially in harsh weather conditions like snow on the ground). Overall remember to keep caution while being a pet owner, and feel free to implement any safety precautions into the area of the zipline. Have fun Zipping!