This simple Marble Run is made using everyday trash (2 toilet paper tubes) and 3D printed connectors. That's it!! Since my kids randomly collect TP tubes (for crafts and art) and I've wanted to try 3D printing something that connects or interacts with everyday objects around the house, this was the perfect solution. Also, every marble run I found for 3D printing on thingiverse was either tiny (for small marbles or ball bearings) or took hours and hours to print!

I've included access to all the design files so this can easily be remixed for different combinations and configurations! Let's see what you can come up with to remix this!

Step 1: Designing the Connectors

I designed all the pieces in Tinkercad. I created them to be as minimal as possible to reduce printing time and cost. You can access the designs below to see how they are made.

Tinkercad Designs:

Step 2: Printing the Connectors

I've published all the STL files and printing instructions on Thingiverse - TP Tube 3D Printed Marble Run

For bulk printing, try multiple pieces (or duplicating pieces) when slicing to print many of them at the same time.

I printed on an Ender 3 w/glass bed: 0.2mm layer height, 100% infill, Black PLA.

Step 3: Cutting the Tubes in Fourths

Next take 2 toilet paper tubes and cut them down their length in half, then cut each side in half again to have 8 pieces that are each 1/4 of a tube. (You will use only 6 of these)

Step 4: Cutting a Notch for the Bottom

In just one of the 1/4 tube pieces you will need a notch cut out of the end about 16mm by 25mm (the size of your thumbnail). (This piece will connect into the 3D printed "bottom" connector further in the steps)

Step 5: Adding the Adaptors for the Ramps

Next, add an 3D printed adaptor connector on each side of 4 of the 1/4 tube pieces by sliding it gently onto the end.

Step 6: Assembling the Side Rails

Take the 1/4 tube piece with the notch on the end and carefully insert it into the 3D printed "bottom" connector as an end rail. (Trim further with scissors as needed.) Add another 1/4 tube piece into the 3D printed "cap", also on end.

Step 7: Constructing the Bottom Ramp

Take one of the 3D printed "down" connectors and slide it down the side rail with the cap. Attach one of the ramps by connecting the adaptors to both sides.

Step 8: Adding Ramps Going Up

Next, attach a "down" connector on one side of a ramp and an "up" connector to the other. Slide the ramp down the side rails until it is in place, slightly angled above the bottom ramp. Repeat for the 3rd ramp.