3D Printed Wall Mounted Marble Run

Hello, I am a 8th grade student at Forest Middle School in VA and am excited to present something that I have put a lot of time into the past few months. This was a very fun project for me as it is the first time I have tried incorporating electronics into 3D printing. I started this project knowing that I wanted to design and 3D print something. AI was able to present the idea and I was able to take it and make it into a physical prototype. If you want to make one yourself, please refer to steps 5-22.

Here are the supplies I used for this project:

• 30 RPM hobby motor (step 13):

https://www.amazon.com/gp/product/B07FYBQ7Z4/ref=ewc_pr_img_1?smid=A19TVI3M6WFVG7&psc=1

• 6V battery holder (step 13):

https://www.amazon.com/gp/product/B07L9M6VZK/ref=ewc_pr_img_2?smid=A2UIWYS7E6PLOL&psc=1

• 8.5 X 14 piece of strong cardboard (step 7)
• About 180 grams of 3D printing filament (step 6)
• 3D printer (step 6)
• Hot glue gun (steps 8, 16, 19, 20, and 22)
• Hot glue (steps 8, 16, 19, 20, and 22)
• Super glue (step 9)
• Tape (steps 13 and 14)
• 10mm metal balls (step 15) (can be found on Amazon)
• Rubber bands (step 11)
• 4 AA batteries (step 13)
• 2 foot wooden dowel that is under 1/4 In in diameter or a 2 foot piece of wood that is under 1/4 in thick (step 14)
• String or yarn (step 22)
• Utility knife or strong scissors (steps 7 and 17)
• Sand paper (step 10)
• Paint (step 18) (optional)

I wanted AI to create the idea. That is a hard task because it is sometimes hard to communicate with AI chatbots. For this project, I started by asking, "What are some cool things that I could design and 3D print?". It responded by throwing out a list of things in the following categories: Organizational Tools, Decorative Items, Functional Objects, Game Pieces, Art Supplies, Models and Figurines, Musical Instruments, Assistive Devices, Sensory Toys, and Animal Enrichment Objects.

I thought that decorative items was a fine place to start. Since I wanted it to have moving parts, I asked the AI, "What is a mechanical decoration that I could 3D print?" It replied by giving me ideas regarding spinning tops, marble runs, and fidget toys. I thought a marble run was a great idea and decided to pursue that.

I was already starting to form an idea, but I asked the AI, "How can I incorporate a marble run into a decoration?" It replied by giving me ideas that I would have never come up with on my own. It also gave me some suggestions to improve the finished product. I decided to go with the simple marble run on board because It would give me the most creativity when making it.

I tried to see if the AI (Canva Image Creator) would generate a picture of a marble run that I could use for inspiration. I was persistent in trying to get an image that I could use but was not able to achieve this as none of them were realistic. I am including this step to show that AI is cool but not yet the solution to everything, and also to show that AI is a very cool tool and can be used in good ways.

The mechanism to lift the marbles from the bottom of the track to the top was the hardest part of this project and the main challenge when designing. I considered a variety of lift mechanisms including a conveyor belt, a Ferris-wheel-like design, and others. I settled on a unique design where the ball is pushed up and falls into a slot. Then, the thing that pushes the ball upward, falls. The ball is then pushed back onto the thing that pushes the ball up, and the process is repeated until the ball reaches the top. I have attached the Fusion 360 file if needed.

I split some parts into smaller pieces to make 3D printing more manageable on smaller printers.

Here are the components:

• AI-Stick (3 parts): The vertical component that moves up and down.
• AI-Slider (3 parts): The horizontal component that moves back and forth.
• AI-Gear (1 part): The gear connected to the motor.
• AI-SliderCase (3 parts): The housing that holds everything together.
• AI-BatteryHolder (1 part): Houses the battery case and the gear.
• AI-Side (5 parts): The edges of the marble run.
• AI-MotorHolder (1 part) Houses the motor and is attached to the AI-BatteryHolder1.

Estimated Filament Usage: 180 grams

The board must be sturdy, flat, and the correct size. Be sure the cardboard piece is at least 8.5" by 14". If you need to trim a board down, I suggest using a straightedge and a utility knife to make straight cuts. If a utility knife is not accessible, a pair of heavy-duty scissors should be fine.

In this step, you will attach the AI-SliderCase and the AI-Side components to the cardboard. I have included a diagram showing where these pieces should be placed on the cardboard. I recommend starting with the AI-SliderCase1 and then proceeding with the other AI-SliderCase components. After that, move on to the AI-Side components. Before gluing, lay out all the pieces to ensure a proper fit. To glue, apply hot glue to the back of the 3D print and press it to the board in the correct location. Make sure to avoid leaving any gaps between the parts when gluing them to the cardboard to ensure everything fits together.

In this step, components from the AI-slider and the AI-Stick will be glued together. I have, again, attached a diagram showing where the parts need to be placed. When gluing, apply a small amount of super glue to one side of the component receiving glue and then press both pieces together firmly, being extra cautious that the parts are aligned. If you are new to super glue, just be warned that it is not fun to have that stuff on your fingers or on your workspace. If you accidentally get glue on your hands, try using hand sanitizer to remove it and make clean up easier by putting newspaper under your workspace.

To ensure the parts move smoothly and avoid getting stuck, sanding after printing is highly recommended. This is especially important for the moving components:

• AI-Stick: Sanding the vertical stick will help it move up and down without catching.
• AI-Slider: Smoothing the horizontal slider will allow it to slide in and out more easily.
• AI-Gear: Sanding the bottom of the gear will help it turn smoother.

You will need two rubber bands for this step, one that is very small and loose and another that is medium-sized and loose. When selecting your rubber bands, choose ones as loose as possible while still pulling the object to the desired location. If they are too tight, the motor may have a harder time lifting or pulling the components. The smaller rubber band will be connected from the AI-Stick to the AI-BatteryHolder, as shown in the video. The medium-sized rubber band should be folded in half and turned into two rubber bands, as shown in the video. It then goes from the AI-Slider to the AI-BatteryHolder.

This is a very simple step where the gear is placed in its spot on the AI-BatteryHolder. Please see the video for a demonstration.

In this step, all of the electronic components of this project will be connected and functional. The first step is installing four AA batteries into the battery case. After that, feed the wires through the hole in the bottom of the AI-BatteryHolder. Once done, place the motor in its socket in the AI-Gear. The following step requires you to tape the AI-MotorHolder to the AI-BatteryHolder and allow the motor holder to fall over the motor into place. After that, place the red wire on the positive side of the motor and have the black wire on the negative side, allowing for a clockwise rotation of the gear. Please note that none of this is permanent, as you will likely have to change some things after testing. 

I added this step after I tested mine and found that the top of the AI-Slider was not sliding out all the way and causing the marble run to jam. I was able to find a way to fix that. What happened was the top of the slider was not moving at all. I figured out that if the slider got extended, then the top of the operational slider would come out far enough. The first thing required for this step is to hot glue another piece of cardboard on top of the current one that is longer than 1 foot and wider than 5 inches. When you glue it, have it hang over the edge of the existing cardboard by about 2 inches. Then, get a 2 foot wooden dowel that is under 1/4 In in diameter or a 2 foot piece of wood that is under 1/4 in thick. With this, tape the bottom of it to the side of the AI-Slider and the top of it to the added cardboard piece be sure that the pole is parallel to the AI-Slider. This is something that may need to be tested before it is made permanent.

Testing a very important step that highly recommended for anyone making this Instructable. So far, everything that has been put together can be undone easily with the exception of removing the frame. This is on purpose because everyone's 3D printers and supplies are slightly different, making everyone's marble run different. You will need to hold the AI-BatteryHolder in place for the testing so I would recommend tipping it on a vertical surface to support it. If you have any issues with your marble run at this point, make the necessary changes to fix it. The videos attached are my first and second tests without the extended slider.

Once you are confident that the lift mechanism works properly, it is time to glue the AI-BatteryHolder1 on to the cardboard. You will need to disassemble the electronics, rubber bands, and the gear for this step. When you glue this piece on the the cardboard, be sure that the AI-Stick is not rubbing against the battery holder as that will hinder your final result. Be sure to reassemble the electronics, rubber bands, and the gear once the battery holder is on.

It's time for the track! For my marble run track, I settled for a simple switchback design meaning that all of my track pieces needed to be the same length. I created a lot of pieces but only needed to use thirteen of them. To create a switchback pattern, use a ruler or measuring tape to mark every 3/4 inch on a 5 inch wide piece of cardboard. After that, take scissors or a utility knife to cut those pieces out.

This step is completely optional but may help your final build look better. For the switchback pattern, take 6 of your 13 pieces and place them on newspaper or regular paper to avoid a mess. I chose to paint mine blue but I am sure that other colors will look great, too. One or two coats of paint should be enough based on your paint thickness. I did two coats on mine and they look great. You may consider trimming these pieces down to make the marble more visible on the track.

For the switchback pattern, the first part of gluing the pieces on is gluing the non-painted pieces. There should be seven of these to work with. Before they are glued down, place them in the correct locations based on the diagram provided. Be sure that you have two on the very bottom ramp to ensure it reaches across the whole space. When I glued mine, I tilted the pieces on a slight angle upwards to make it harder for them to fall off. I also only glued the bottom of the pieces on so that glue did not interrupt the path of the marble.

The next step is gluing the painted pieces on top of the non-glued pieces. This is to help the marble not fall off and to make the project more visual appealing. There should be 6 remaining pieces to work with for this step and they will all be glued on top of the already existing track. When gluing, glue the bottom of the pieces and then place them on the board. Be careful not to let the glue spread onto the track as that will interrupt the path of the marble as it is falling.

This step is not necessary but may improve the look of the final product. This is the time that you may remove any unnecessary cardboard from the marble run. I was able to remove a fair amount of cardboard from the very top to make it look nicer.

The final step of this project is attaching a string to the back of the marble run for mounting purposes. For this, take a piece of yarn or string that is 18 In long and fold it in half. Place that string on the back side of the marble run section on the cardboard. Take your hot glue gun and put a lot of hot glue on each side of the string. Hang it up on the wall in a safe location. This is the last step before you can turn it on and watch the marble go over and over again all on its own!

Well, that's it! I hope you enjoyed making your very own 3D printed wall mounted marble run. I know I sure had fun and I learned a lot. This was a project full of perseverance as, at one point, six different parts of the marble run were not working correctly. I was able to fix the problems one by one until I got the finished product. Thanks for visiting!