🎨 My First 3D Prints · Episode 6 of 8 · See All Episodes
🖥️ Episode 6 · Intermediate · TinkerCAD

Marble Run
Channels, Ramps & Physics

Build a marble run with ramps, funnels, and zigzag channels, a hands-on 3D design project that teaches you about gravity, slopes, and structural support!

👶 Ages 8+ ⏱️ ~1.5 Hours 🖥️ TinkerCAD ✓ Free 👨‍👧 Parent & Child
🔲 Channels 📐 Ramps 🔄 Rotation 🏗️ Support Structures ⚙️ Physics Design 🌉 Overhangs
🏗️ Let's Build! Start Step 1 ← All Episodes 🖨️ Print Guide
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🧊 This is what you're building
drag to spin · scroll to zoom · this exact model is what the steps below create ⬇️ Download the finished STL
1
📝
Plan the Marble Run Layout
Sketch your path from top to bottom, think about gravity and zigzag patterns
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Goal for this step

Plan out the path of your marble run on paper before you start building in TinkerCAD.

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Parent note: TinkerCAD runs in the browser at tinkercad.com, it's free! Create a free Autodesk account. For under-13s, a parent creates the account. Grab a pencil and paper for sketching the layout first.

Sketch your marble run

  • 1Grab a piece of paper and draw a tall rectangle, this represents your back plate.
  • 2Starting from the top, draw a funnel shape where the marble enters.
  • 3Draw angled lines going left and right in a zigzag pattern, these are your ramps.
  • 4Think about gravity, the marble needs to roll downhill on every ramp.
  • 5Add a landing area at the bottom where the marble finishes its run.
funnel in ramp ↘ ↙ ramp ramp ↘ landing area 🏁
Gravity does all the work, so every line must tilt downhill. Sketch the zigzag first: marble in at the top funnel, left-right-left down the ramps, rest at the landing area.
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The zigzag pattern is important, it slows the marble down so you can watch it travel, and it keeps the run compact instead of being one long slope.
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Knowledge Check
+15 XP
Why do marble runs use a zigzag pattern instead of one straight slope?
AIt looks cool
BIt slows the marble and makes it visible longer
CIt's easier to build
2
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Create the Back Plate
Build a tall flat box as the mounting surface for all your ramps
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Goal for this step

Create a tall, flat box shape that acts as the back plate, the surface that holds all the ramps in place.

Build the back plate

  • 1Open TinkerCAD and create a new design. Name it "Marble Run".
  • 2Drag a Box shape onto the workplane from the shapes panel on the right.
  • 3Click the box and use the white corner handles to resize it to approximately 100mm wide × 150mm tall × 5mm deep.
  • 4You can type exact dimensions in the size fields that appear when you drag a handle. The back plate should be thin, only 5mm deep.
  • 5This back plate is the foundation, all ramps and funnels will be attached to the front of it.
100 mm 150 mm side: 5 mm everything attaches to this
A tall thin canvas. 100 × 150 × 5 mm, like a postcard stood upright. All the ramps, tubes and funnels stick onto the front of it.
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Hold Shift while dragging a corner to resize proportionally. You can also click a dimension number and type an exact value.
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True or False?
+15 XP
The back plate holds all the ramps in place.
The back plate should be thin (about 5mm deep).
Marble runs don't need a back plate.
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Knowledge Check
+15 XP
What is the main purpose of the back plate?
ATo make the marble run heavier
BTo act as a ramp for the marble
CTo provide a mounting surface for all the ramps and channels
3
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Build the First Ramp
Create a channel shape and rotate it 15 degrees for a gentle slope
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Goal for this step

Build your first ramp by resizing a box into a channel shape and rotating it to create a gentle downward slope.

Create and angle the ramp

  • 1Drag a new Box onto the workplane. This will become your first ramp.
  • 2Resize it to approximately 60mm long × 24mm wide × 3mm tall, a flat, elongated shape.
  • 3Look for the curved rotation handles around the shape, they appear as arcs near the corners.
  • 4Grab the rotation handle and rotate the ramp by 15 degrees. You'll see the angle displayed as you rotate.
  • 5Position the ramp near the top of the back plate, tilting downward to one side.
rotate 15° 15.0° FRONT VIEW · the marble rolls down the tilt, left to right
15° is the sweet spot: steep enough that the marble never stalls, gentle enough that it does not fly off the end. Watch the angle readout as you drag the rotation handle.
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A 15-degree angle creates a gentle slope, steep enough for the marble to roll, but slow enough to be fun to watch!
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Fill in the Blanks
+15 XP
To angle a ramp, you rotate it by degrees. The tilt direction should be so the marble rolls along it.
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Knowledge Check
+15 XP
What angle creates a gentle slope for a marble run ramp?
A90 degrees, straight down
B15 degrees, a gentle tilt
C0 degrees, completely flat
4
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Add Walls to the Channel
Place thin tall boxes along each side of the ramp to keep the marble on track
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Goal for this step

Add two thin walls along each side of the ramp to create a channel that guides the marble.

Build the channel walls

  • 1Drag a new Box onto the workplane. This will become one wall of the channel.
  • 2Resize it to be the same length as your ramp, but only 2mm thick and 10mm tall.
  • 3Position it along one edge of the ramp, so it sits on top like a guardrail.
  • 4Duplicate the wall (Ctrl+D) and move the copy to the other edge of the ramp.
  • 5Select both walls and the ramp, then click Group (Ctrl+G) to combine them into one piece.
LOOKING ALONG THE RAMP 20 mm between the walls · marble is 16 mm · ✓ room to roll walls: 2 mm thick, 10 mm tall
Walls turn a ramp into a channel. One guardrail on each long edge, grouped with the ramp. With the 24 mm ramp, the inside gap stays a marble-friendly 20 mm.
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Without walls, the marble would roll off the side of the ramp! The walls create a channel that guides it along the path.
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Design Challenge
+20 XP
Fill in the blanks for the channel wall dimensions:
Wall height = mm Wall thickness = mm
💡 Hint: Walls need to be tall enough to stop the marble but thin enough to not waste material.
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Knowledge Check
+15 XP
Why do ramps need walls on each side?
ATo keep the marble on track and prevent it from rolling off the edge
BTo make the ramp stronger
CWalls are only decorative
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Create a Funnel at the Top
Build a cone and cylinder hole to make a funnel entry point
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Goal for this step

Create a funnel shape at the top of the marble run where the marble enters and gets guided onto the first ramp.

Build the funnel

  • 1Drag a Cone shape onto the workplane. Resize it to about 30mm diameter × 25mm tall.
  • 2Now drag a Cylinder onto the workplane. Make it about 20mm diameter × 30mm tall.
  • 3Click the cylinder and change it to a Hole (click the "Hole" button in the inspector panel).
  • 4Position the cylinder hole inside the centre of the cone, so it cuts through the middle.
  • 5Select both the cone and the cylinder hole, then click Group (Ctrl+G). The hole cuts through the cone, creating a funnel!
  • 6Position the funnel at the very top of your marble run, above the first ramp.
CONE + CYLINDER HOLE Group FUNNEL · CUT AWAY marble drops in the crater, shoots out the bottom
The cylinder hole must run all the way through the cone, top to bottom, before you Group. You end up with a volcano shape whose crater guides the marble onto ramp one.
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The funnel makes it easy to drop the marble in, the wide top guides it down to the narrow opening and onto the first ramp.
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Put It In Order
+15 XP
Click these steps in the correct order to create a funnel:
Group the cone and cylinder hole together
Place a cone shape on the workplane
Position the funnel at the top of the marble run
Add a cylinder hole inside the cone
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Knowledge Check
+15 XP
What is the purpose of the funnel at the top of the marble run?
ATo make the marble spin
BTo guide the marble from a wide opening down onto the first ramp
CTo hold multiple marbles at once
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Connect Ramp Sections
Alternate left-right zigzag ramps, each angled in the opposite direction
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Goal for this step

Duplicate your first ramp and arrange multiple ramps in a zigzag pattern, alternating the tilt direction.

Build the zigzag

  • 1Select your completed ramp (with walls) and press Ctrl+D to duplicate it.
  • 2Move the duplicate below the first ramp and flip it, rotate it so it tilts in the opposite direction.
  • 3The end of the first ramp should be directly above the start of the second ramp, so the marble drops from one to the next.
  • 4Duplicate and flip again to create a third ramp below the second. Keep alternating!
  • 5Aim for 4-5 ramps in total, forming a zigzag path from top to bottom.
each ramp's END sits just above the NEXT ramp's start duplicate → flip the angle → shift down · 4-5 ramps total
Mirror each copy. Ctrl+D the walled ramp, rotate the copy to -15° (tilting the other way), and slide it down so the marble falls off one ramp straight onto the next.
✅Checkpoint: trace the path with your eye from the funnel: every ramp end should hang OVER the start of the ramp below it. Any gap the marble has to jump sideways is a spot where it will escape.
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Make sure each ramp overlaps slightly with the one above, the marble needs a clear drop point from one ramp to the next.
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Predict What Happens
+15 XP
You've built three ramps, but they all tilt the same direction (left to right) instead of alternating.

What will happen when the marble reaches the end of the first ramp?
AThe marble flies off the side instead of landing on the next ramp
BThe marble rolls backwards
CThe marble stops moving
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Knowledge Check
+15 XP
Why must alternating ramps tilt in opposite directions?
AIt makes the model lighter
BIt uses less filament
CSo the marble drops from the end of one ramp onto the start of the next
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Add a Drop Section
Create a vertical tube between levels for dramatic drops
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Goal for this step

Build a vertical tube that the marble falls through between ramp levels, adding excitement and variety to the run.

Build the drop tube

  • 1Drag a Cylinder onto the workplane. Make it about 22mm diameter × 40mm tall.
  • 2Drag another Cylinder and make it 18mm diameter × 45mm tall. Set it as a Hole.
  • 3Centre the hole cylinder inside the solid cylinder. The hole must be slightly taller to cut through both ends.
  • 4Group them (Ctrl+G) to create a hollow tube.
  • 5Position the tube so its top opening is at the end of one ramp and its bottom opening leads to the next ramp below.
CYLINDER + TALLER HOLE Group THE DROP SECTION top opening under a ramp end · bottom over the next ramp
The hole is 5 mm taller than the tube on purpose, so it pokes out both ends and cuts a clean passage. 18 mm inner diameter gives the 16 mm marble a smooth fall.
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Drop sections add drama! The marble disappears into the tube and pops out below. Kids love this part!
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True or False?
+15 XP
The tube's inner diameter must be bigger than the marble.
Drops slow the marble down.
Tubes are made by grouping two cylinders (one solid, one hole).
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Knowledge Check
+15 XP
How do you create a hollow tube in TinkerCAD?
AUse the tube shape from the library
BPlace a smaller cylinder hole inside a larger cylinder, then group them
CStretch a ring shape vertically
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🛬
Create Landing Pads
Add flat platforms at each level transition to catch the marble after drops
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Goal for this step

Add flat landing pads at each level transition so the marble has a surface to land on after dropping from a tube or ramp.

Build landing pads

  • 1Drag a Box onto the workplane. Resize it to about 25mm × 25mm × 3mm, a small flat platform.
  • 2Position it directly below a drop tube, so the marble lands on it after falling.
  • 3Add walls on the sides that face open air, the marble shouldn't bounce off the pad!
  • 4Make sure the landing pad connects to the next ramp, the marble needs to roll from the pad onto the ramp.
  • 5Duplicate and position landing pads at every level transition in your marble run.
wall on the open side, no bouncing away! 25 × 25 × 3 mm pad · catches the drop, feeds the next ramp
Every drop needs a catcher. The pad sits directly under the tube, has a wall on any side facing open air, and touches the next ramp so the marble rolls straight on.
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Fill in the Blanks
+15 XP
A landing pad catches the marble after a . It connects the tube exit to the next .
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Knowledge Check
+15 XP
What is the purpose of a landing pad?
ATo make the marble bounce higher
BTo slow the marble to a complete stop
CTo catch the marble after a drop and guide it onto the next ramp
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🏗️
Add Side Supports
Build L-shaped brackets or triangle supports so the structure stands freely
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Goal for this step

Add structural supports so the marble run can stand upright on its own without falling over.

Build the supports

  • 1Drag a Box onto the workplane. This will form the base of an L-shaped support.
  • 2Resize it to about 20mm wide × 40mm long × 5mm tall, a flat foot.
  • 3Add another box standing upright: 20mm wide × 5mm deep × 40mm tall. Position it at one end of the flat foot.
  • 4Group both pieces to create an L-shaped bracket. Position it at the bottom edge of the back plate.
  • 5Duplicate the support and place one on each side of the back plate for stability.
SIDE VIEW L-bracket: flat foot + upright grouped, hugging the plate use TWO, one at each side edge, so the run stands up on its own
The plate cannot balance on a 5 mm edge. Two L-brackets, one per side, act like bookends. The foot points forward, the upright glues flat against the plate.
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The support should touch both the base (the surface it sits on) and the back plate, creating a stable triangle of force.
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Design Challenge
+20 XP
Fill in the blanks for structural support design:
Support width = mm The support should touch both the and the back plate.
💡 Hint: The support creates an L-shape connecting the flat surface to the vertical back plate.
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Knowledge Check
+15 XP
Why does the marble run need side supports?
ASo the structure can stand upright without falling over
BTo make the marble go faster
CTo add more ramps
10
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Test Marble Clearance
Check that channels are wide enough for a 16mm marble to pass through
Locked
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Goal for this step

Verify that every channel, tube, and opening is wide enough for a standard 16mm marble to pass through smoothly.

Check all clearances

  • 1A standard marble is 16mm in diameter. All channels and tubes need to be at least 18mm wide.
  • 2Use the Ruler tool in TinkerCAD (click the ruler icon on the right toolbar) to measure channel widths.
  • 3Check the inner diameter of any tubes, it should be at least 18mm.
  • 4Check the channel width between walls on every ramp, at least 18mm between the inside edges.
  • 5Check the funnel opening at the bottom, wide enough for the marble to pass through.
16 mm marble 18 mm minimum everywhere the marble goes ✓ 1 mm of daylight each side keeps it rolling smoothly
Play quality inspector before exporting. Measure every channel, tube and funnel exit with the Ruler tool: anything under 18 mm WILL trap the marble on the printed model.
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The extra 2mm clearance (18mm channel for a 16mm marble) accounts for 3D printing tolerances, printed parts are never perfectly exact.
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Fill in the Blanks
+15 XP
A standard marble diameter is mm, so channels need a minimum width of mm.
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Knowledge Check
+15 XP
Why should channels be 2mm wider than the marble?
ATo allow tolerance for 3D printing imperfections
BTo make the marble go faster
CSo two marbles can fit side by side
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🏛️
Add Decorative Elements
Add arches, pillars, and a flag at the finish using various shapes
Locked
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Goal for this step

Make your marble run look amazing by adding decorative elements like arches, pillars, and a flag at the finish line.

Decorate your marble run

  • 1Create an arch: place a cylinder, add a cylinder hole halfway through it, and group. Position it over a ramp section.
  • 2Add pillars: use thin, tall cylinders placed at the corners of the back plate.
  • 3Create a flag: use a thin box (pole) with a small flat box (flag) at the top. Place it at the finish.
  • 4Try adding small spheres as decorative balls along the edges.
  • 5Make sure decorations don't block the marble path, they should be purely visual!
arch over a ramp corner pillars finish-line flag DECORATION IDEAS
Decorate the edges, never the path. Arches, pillars and flags make the run feel like a theme park, but hold each one up against the marble route and make sure nothing pokes into it.
🎉
This is your creative moment! Add as many or as few decorations as you like. Some builders add towers, bridges, or even tiny people!
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True or False?
+15 XP
Decorations affect the marble's path.
Arches can be created using cylinder holes.
Decorations make the build more fun and personalised.
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Knowledge Check
+15 XP
How do you create an arch shape in TinkerCAD?
AUse the arch shape from the library
BPlace a cylinder hole through the bottom half of a cylinder, then group
CBend a box shape using the curve tool
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📤
Export & Learn About Supports
Export your STL and learn about support material for overhangs
Locked
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Goal for this step

Export your marble run as an STL file, learn about support material, and get it ready for 3D printing.

Export and prepare for printing

  • 1In TinkerCAD, click Export (top right). Choose .STL format and save the file.
  • 2Open your slicer software (e.g., Cura, PrusaSlicer). Import the STL file.
  • 3Your marble run has overhangs, the ramps stick out from the back plate with nothing underneath. These need support material.
  • 4Enable Supports in your slicer settings. The slicer will automatically add temporary support structures under overhangs.
  • 5Check the preview in your slicer, you'll see the supports highlighted in a different colour.
  • 6After printing, carefully remove the support material by snapping or cutting it away.
IN THE SLICER support pillars, added automatically by the slicer AFTER PRINTING ✓ snap the supports off clean overhanging ramp!
Tick "Enable Supports" in the slicer. Ramps jutting out sideways cannot be printed on thin air; the slicer scaffolds them with break-away pillars you remove after printing.
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Parent note: Support removal can involve sharp edges. Help younger children remove supports safely. A pair of flush cutters (side cutters) makes this much easier.
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Put It In Order
+15 XP
Click these steps in the correct order to export and print:
Enable supports for overhangs in slicer settings
Print the model
Export the STL file from TinkerCAD
Check the preview to verify supports look correct
Open the STL in your slicer software
🧠
Final Knowledge Check
+15 XP
When do you need support material for 3D printing?
AFor every 3D print regardless of shape
BOnly when printing in colour
CFor overhangs greater than about 45 degrees that have nothing underneath
🛠️ Printed it and something's not right?
The marble stops halfway down a ramp.
The ramp angle is too shallow, anything under about 10° risks stalling. 15° is the sweet spot. Also wipe the channels, printing dust slows marbles surprisingly well.
The marble flies off the side.
Walls too low or a ramp too steep. Walls should be 10mm tall, and where a ramp ends the next one must start directly beneath it (step 6's checkpoint).
The marble jams in a tube or channel.
Somewhere is under 18mm wide (step 10). Find the pinch point, widen it in TinkerCad, and re-print that part, or sand the inside if it is close.
The channels feel rough where the supports were.
Normal! Support material leaves scars. Sand the channel floors smooth with fine sandpaper and the marble will run much faster.
🎉🏗️🔮🎊⚡
You Built a Marble Run!

Amazing, you've designed a complete marble run with ramps, funnels, drop tubes, landing pads, supports, and decorations. Now print it and watch the marble roll!

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