How to DIY a marble run with PVC pipe and not much else

Updated Oct 12 2015
Guest post by Sean Kaloi

A few weeks ago I picked up Do-It-Yourself Early Learning: Easy and Fun Activities and Toys from Everyday Home Center Materials at my local library and quickly realized I had found my new favorite kid-related book. It's filled with activities kids and parents can build using stuff they most likely have at the house (or that's easy to find). One of the activities, Pipe Construction Set (page 184) jumped out at me — you basically give your kid a set of PVC pipes and fittings, dump them on the floor, and see what he or she builds.

I thought it would be cool to take the project one step further and attempt to craft a marble run (like this: Quercetti Super Marble Run) out of the pipe. Since PVC is notoriously toxic, I don't recommend this project for infants or really young kids… but if you're curious, here's how I did it:

What you need

Tools

Materials

How you do it

Basic PVC Construction Set

  1. Cut various lengths of PVC with your chosen cutting tool. PVC cutters make smoother edges and require less sanding than using a hacksaw. Home-building stores often have cutters available for you to obtain the lengths necessary before you even check out.
  2. Buy couplers and various fittings. This is quite important because the fun stuff happens when you make shapes with the piping.
  3. Sand pipes and check for sharp edges. Get rid of them.
  4. Paint the set if you like. Make sure your paint is going to stay on the PVC and not gum the joints.
  5. Throw everything in the floor for kids to make messes.

Bending PVC for custom shapes

PVC's Heat Distortion Temperature (Softening Temperature) is 92C/197F. I was not about to cook it in the oven (that shit is POISONOUS), so I built a Kyoto Box Solar Cooker out of a cardboard box, aluminum foil, black paint, a pane from a picture frame, and foam board. The foam board isn't necessary, but I thought it was a cool addition and I had some scraps at work.

  1. If you don't have foam board, skip to step 2. Estimate the lengths of foam necessary to line the inside of the box and simply squeeze them together. You should only need five pieces to do this.
  2. Paint the inside black as you can. That way more energy is absorbed into your cooker.
  3. Line the box flaps with aluminum foil (shiny side up). These are mirrors to redirect more light into your cooker. You will have to angle the flaps according to the Sun's location in the day sky.
  4. Place glass pane over opening to create greenhouse effect inside your cooker. Go ahead and have your PVC piece inside and ready to be softened.
  5. Check it periodically. When it's swelling, it's ready to bend. In Alabama Hell it takes about 20 minutes.
  6. BE CAREFUL! It's really hot! Using gloves or a towel, bend it like you want to, being careful not to crimp it.

Cutting PVC lengthwise for visible marble running

This was an after thought. I did it with scrap PVC as an experiment. The pieces cut rest in connectors, but don't fit tightly. It makes the "marble run" facet of the toy more fun though. AND DON'T DO THIS WITHOUT PROPER TOOLS AND SAFETY GEAR! Really, you should probably play it safe and just buy clear PVC.

  1. Build saw horses with a board for attaching PVC securely.
  2. Clamp PVC tightly so there's no slipping.
  3. I flipped a Skil saw blade over so the teeth rubbed through the PVC (melting it with friction) instead of using the usual sawing action. Note: this isn't how a Skil saw is meant to be used — flip the blade at your own risk. Definitely know what you're doing!
  4. Saw it slowly and carefully. With your face protection ON! You may have to trim edges to size.
  5. Sand it well, there may be some jagged edges.

Marble Run

Use your PVC construction set to build your marble run the way you like. The joints do not allow for easy marble rolling, so you need to make sure the grade is steep enough to allow the marble to roll over the joints. After doing this a few times, we've become better at manipulating it to do what we want it to do, but if you just want a marble run, it maybe worth the cash to buy one. If you want a versatile construction toy that does many things including being a mediocre marble run, than this project's for you!

  1. Just to reiterate how dangerous working with hot PVC can be, there is a particular type of liver cancer that is found in people who make PVC. It's not hazardous once the PVC is solid, but heating it would release the dangerous gas.

    One of my Environmental Science profs was studying it back in the day.

  2. Hello! I love this idea and have been wanting to give my 4 year old some pvc pipes as construction material for some time. Are you saying that it's toxic only when sawing and heating the PVC pipe? Is it safe for children to construct with as long as they aren't cutting into it, heating it or drinking water from the tubes?

    • PVC is a safe harmless material that is used for distributing drinking water among other things. When PVC gets to high temperatures (ie burning) it releases dioxin which is a very hazardous chemical. Otherwise it is perfectly child safe.

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