- Difficulty
- Intermediate
- Build time
- 55-90 min
- Estimated cost
- $0-$5
- Age range
- 10-18
- Workspace
- A clear table about 90 cm wide
The finish line
What you will build
The tower reaches at least 60 cm, supports 500 grams for ten seconds, and remains standing after a gentle table tap.
Learning goals
- Identify how downward top load and small side disturbance produces stable compression paths to the base.
- Construct and explain a static loading-to-small structural deflection system.
- Measure how vertical brace spacing changes performance.
- Diagnose losses caused by column buckling and joint slip.
Before you build
Materials, tools, and safety
Reuse-material cost: $0-$3 with reused materials. Supervision: Adult help recommended for sharp or heated tools.
Tools
- Ruler
- Pencil
- Scissors
- Timer or phone stopwatch
Low-cost swaps
- Use reclaimed paper and packaging while keeping material limits equal for every team.
- Replace metal test weights with labeled bags of coins or washers.
- Use newspaper sheets cut to equal mass and labeled bags of coins for load.
Project-specific safety
- Keep load and drop tests below shoulder height and away from faces.
- Clear the test zone before releasing moving objects or suspended loads.
- Keep the tower on the floor during final loading, add mass from the side, and use bagged weights that cannot scatter.
Orient the build
Place the build so downward top load and small side disturbance is on your left and stable compression paths to the base is on your right. Call the side facing you the front, the far side the back, the tabletop the bottom, and the opposite face the top.
Build it
Step-by-step instructions
Step 1
Set the constraints
Limit paper, tape, footprint, and 500-gram load.
Draw a 30 × 30 cm maximum base square.
Step 2
Choose a frame plan
Sketch three- or four-column geometry with brace levels every 20 cm.
Mark where the load plate sits.
Step 3
Roll equal columns
Roll paper tightly around a pencil and tape the seam.
Make matching diameters and lengths.
Builder checkpoint: After roll equal columns, the first subassembly should stay aligned when handled gently.
Step 4
Build the base level
Join columns with horizontal beams and diagonals.
Check both diagonals of the footprint for squareness.
Watch for: If this stage binds or drifts, inspect frame twist before adding more parts.
Step 5
Add upper levels
Extend columns with overlapped sleeves and brace each new bay.
Stagger joints between sides.
Step 6
Install the load plate
Center a stiff plate across every top column.
Prevent it from sliding.
Builder checkpoint: After install the load plate, operate the build slowly and confirm that stable compression paths to the base begins without binding.
Step 7
Run staged loading
Add 100 grams every five seconds while watching columns.
Stop at sudden lean or permanent buckle.
Step 8
Perform the stability tap
After passing 500 grams, tap the table gently from a marked distance.
Record top movement and recovery.
Builder checkpoint: At the final checkpoint, The tower reaches at least 60 cm, supports 500 grams for ten seconds, and remains standing after a gentle table tap.
See the engineering
Why it works
- Input
- downward top load and small side disturbance
- Output
- stable compression paths to the base
- Motion
- static loading-to-small structural deflection
- Energy losses
- column buckling, joint slip, base tipping, frame twist
Why this works
Braced compression structure
Columns carry the load downward, while diagonal braces prevent the frame from changing shape. A wide base keeps the combined center of mass inside the support area.
Look for: Watch the longest unbraced column and mark whether it bends sideways before any material crushes.
Where the energy goes
Efficiency and losses
The ideal model leaves out column buckling, joint slip, base tipping, frame twist. These effects turn some input energy into heat, sound, vibration, or unwanted motion, so measured performance will be lower than an ideal calculation.
Look for: Run the build slowly and locate the first place where column buckling becomes visible or audible.
Math bite
Calculate slenderness
Formula: slenderness ratio = unsupported length / member width
- Unsupported length = 20 cm
- Tube width = 2 cm
Substitute: ratio = 20 / 2 = 10
Result: This member has a slenderness ratio of 10.
Shorter braced lengths are less prone to buckling.
Paper tubes are not solid, uniform engineering columns.
Make it behave
Test, troubleshoot, and tune
Controlled test
Start here: Load the first 20 cm frame with 100 grams before building taller.
Success looks like: The completed tower holds 500 grams for ten seconds and survives one gentle tap.
Measure: Height, load, top sway, first buckle, and material use.
Change: vertical brace spacing
Keep constant: paper, tape, footprint, load plate, loading rate, and floor
- 30 cm spacing
- 20 cm spacing
- 15 cm spacing
| Symptom | Likely cause | Confirm it | Fix |
|---|---|---|---|
| One column bows | Unbraced length is too great | View each face during low load | Add a diagonal or mid-level tie |
| The tower twists | Faces lack triangulation | Hold base and nudge top lightly | Add opposing diagonal braces |
| The base tips | Footprint is narrow or load off-center | Project the load position downward | Widen base and center plate |
| A splice crushes | Overlap is short or all joints align | Inspect the first collapsed seam | Use longer sleeves and stagger splices |
Choose your tradeoff
Shorten unsupported column lengths before adding more paper to every member. Extra bracing increases stability but also adds mass and joint complexity.
Keep experimenting
Try another version
Forty-centimetre target
Use the same load with fewer levels.
Efficiency score
Multiply passing height by load and divide by tower mass.
Lateral test
Measure top displacement from equal gentle side pulls.
Build together
Classroom and access options
Classroom version
Teams can compare vertical brace spacing while keeping paper, tape, footprint, load plate, loading rate, and floor. Assign builder, tester, recorder, and explainer roles; have each team predict the result before collecting three trials.
Access adaptations
- Assign varied roles such as designer, builder, tester, recorder, and presenter.
- Provide pre-measured materials and a visual checklist when helpful.
- Use rolling mandrels, pre-measured tape strips, and team roles for member production, assembly, loading, and observation.
Reflect on the design
- How did vertical brace spacing change the measured result?
- Where did column buckling affect the build most strongly?
- What evidence shows that braced compression structure explains the motion?
- Which change would improve stable compression paths to the base without creating a new problem?
Glossary
- Braced compression structure
- Columns carry the load downward, while diagonal braces prevent the frame from changing shape.
- Input
- The action or energy supplied to a system; here it is downward top load and small side disturbance.
- Output
- The useful response produced by a system; here it is stable compression paths to the base.
- Efficiency
- The fraction of input energy that becomes useful output instead of friction, sound, heat, or unwanted motion.
Build your dreams
One build can start the next.
Share what you learned, change one variable, and help another builder understand what worked.
Explore more guidesSources and build notes
A common classroom engineering challenge implemented with original constraints, diagrams, and measurement guidance.
- Classroom challenge basis: A controlled-variable engineering activity with original constraints, scoring ideas, and measurement guidance.
Written and edited by BrickLabClips. Published 2026-07-22; updated 2026-07-22.