Introduction: $50 DIY Zipline Trolley

About: Welcome to my Instructables channel where I'll share my wacky and unique creations that hopefully others find useful, or better yet, inspire an evolution of even better ideas!

I made this from stuff laying around in the garage several years ago and simply strung it up in our garage for the kids to play on. When the kids were a little older they had a "Land Lab" trip (Montessori School Activity) and I took this on the trip while attending as a chaperon and strung it up over a Wash (dry river in Arizona) for the entire class to play on.

It was a super hit, and to this day is still installed at the same site and gets used twice a year by each class. That's why I can't provide detailed images of the build. And I'll be going off of memory on how I built it.

Total price for all the parts needed will cost much much less than even the cheapest commercial one you can find on Amazon and this will be much more durable and reliable. I'd estimate the cost (assuming you have proper tools like drill press and metal cut-off saw) to be around $50.


  1. Qty 2 - "T" Braces from Home Depot
  2. Qty 10 - Spacers
  3. Qty 2 -Roller Bearings from Ace Hardware
  4. 1/4" Hardware (Screws, washers, and nylon locknuts)
  5. 1/2" All-Thread, fender washers, and nylon locknuts
  6. Pipe (for handles)


  1. Drill press (for 4 holes)
  2. Metal cut-off saw (for 3 pieces of pipe and one section of all-thread))

Step 1: Primary Structure

The "T" braces from Home depot (only $8) serve as the primary structure for the trolley. There are a few different sizes, but I'm pretty sure the 12"X8" was the size I used.

Its also galvanized so it will hold up really well for outdoor use.

CAUTION: Before assembling, round off all the corners and edges. These are stamped out so they can have very sharp edges.

Step 2: Drill Holes

You want the roller bearings to sit flush inside the braces. Also you want the cable to run freely through the center and not rub any of the spacers.

Precise dimensions are not needed, just eyeball it.

TIP: Clamp two together and drill both at the same time.

Step 3: Assemble Bearing & Spacers

Going off memory now, but I think the spacers were 7/16" tall (1/4" ID aluminum spacers). You want to place a spacer at each hole that's already present in the brace except the top two corners where the roller bearings are now located. (First image above.)

For the roller bearings also include a 1/16" thick washer sized to fit the inner portion of the bearing (Second image above). And you need this washer on both sides of the bearing. It will ensure the roller bearing is free to spin smoothly while ensuring that the spacing between the two braces ends up as 7/16":

  • 5/16" form the bearing itself
  • 1/16" thick washer
  • 1/16" thick washer
  • Which equals the spacer height of 7/16"

Step 4: Assemble Top Brace

Place the top brace over the lower brace with all the roller bearings, washers, and spacers in position. Ensure the top brace is oriented correctly as it has a "Top" and "Bottom".

Install 1/4" hardware through all 10 joints. I remember using a piece of tape over the heads of the screws so you can flip the whole assembly over to attach the nuts on the opposite side.

Tighten all these joints fully and grind off any extra length of screws protruding from beyond the nut for safety.

NOTE: Depending on how you will be running/attaching the cable, you may need to "permanently" install the cable to the trolley during this step. For example, if your cable already has loops in the ends, they will not be able to be fed through the small openings, and as such, the cable would need to be laid inside before attaching the top brace.

Step 5: Install the Handles

I had some scrap pipe that was chrome plated and used that at the time, but any pipe with about a 1" outer dimeter will work fine.

  1. Cut two lengths of pipe for each handle
  2. Cut one 7/16" tall piece of pipe to serve as the center spacer
  3. Cut a section of all-thread, I think I used 1/2", long enough to go through both handles, the trolley frame, 4 fender washers (one on each side of each handle), and the two nuts at the end
  4. Secure both ends with nylon lock nuts
  5. Grind off any extra length of the all-thread for safety

Step 6: Finished - Go Have Some Fun

My biggest concern for this was for the girls with long hair and it somehow getting tangled inside, but that never happened. As a precaution though, if I were to make another, I would find a way to block off the internals.

TIP: While mine has held up well, I'm sure those bearing are probably shot by now. They are made for the bottom of sliding glass doors, so are not intended for this application. If you could find similar size roller bearing that are sealed and made for high speed, they would likely make for a much faster/smoother ride.

Thanks for taking the time to read through my Instructable. Please send me any questions or comments you might have. I try to answer them all. Stay safe and healthy! Happy Zipping!