Science and Engineering Project – Reflect and Share


This is the link to the video of the final product of the safe looking from the outside.

Purpose of the Safe

This safe can be useful in storing small and valuable items that are easily lost like accessories, USB, or earphones especially for people who often go searching their entire room to find a single item that they don’t remember where they put.

Impact on the Environment

The main material for this safe is wood; other than wood, the only materials used were rubberband and metal from the hinge. They are all materials that do not harm the environment.

How Does This Work?

The safe mainly works by using the elastic potential energy and the repelling forces of two magnets. Inside the safe, there is a small seesaw; one side attached to pieces of magnets and the other side to a triangular wood piece that hangs on to a hole in order to lock. When the card that has a magnet glued on swipes through the rectangular hole, the magnet inside the safe repels and makes the seesaw tilt toward the other side so that the triangular wood piece is detached from the locking hole. Here, the rubber band is used to prevent the seesaw and the magnet from moving freely and it pushes back the magnet to its position of locking in order to lock the safe again.


Problems/Difficulties and Solution

Before I started this project, a teacher pointed out that a safe made out of cardboard could be too insecure to achieve its purpose. I kept that in mind thinking about how I can improve the security and started the project using cardboard. However, I thought I would be a better idea to start with a more firm and reliable material. Starting from the second day, I restarted my project and used wood as my base material.

Another problem I faced was the opening process of the door. The wood I used for the door was too thick to open smoothly. Making changes to my original plan, I drilled hinges on the wood to make the opening process work. However, it was still not smooth enough.

Lastly, the rubber band did not have enough energy to push the magnet back to its locking position and force the door open and close automatically. As a result, a card has to be swiped again in order to lock. It was one of the biggest problems that I could not find a better solution to.


Science and Engineering Project – Create and Improve

Day 1

I originally started making the safe with cardboard; however, the cardboard was more fragile and thinner than I thought. Accordingly, I changed my plan from using cardboard to wood.

Day 2


I used the laser cutting machine to cut out variously-sized woods and glued the pieces together using hot glue.

Day 3

I added significant parts of the lock and glued it on to the biggest piece of wood, acting as the door.

Day 4


The wood was a little thick and hard to open without anything connecting them, so I drilled hinges on to the door, and it opened smoothly.

Since the hole for the card was too small and rough for the card to swipe through, I used sandpaper to smoothen the hole and make it a little larger.

Testing the Lock

This is a link to a video of me testing the lock of my safe.

The door is supposed to open automatically, but the size of the door fits too tightly to the frame, so it is disabled to be pushed out without human force.

Science and Engineering project – Develop and Plan

SAFE Unlocking with Card


3(15cm x 18cm), 2(18cm x 22cm), 2(16cm x 22cm), 2(2.5cm x 13cm), (4.5cm x 7cm), (1.3cm x 13cm) (1.8cm x 3cm) cardboard, two small magnets, rubber band, chopstick, popsicle stick

*added materials when improving* Wood, hinge

Needed techniques

Cutting cardboard and wood and gluing pieces together

*additional techniques needed* laser cutting the wood and drilling hinges onto the wood


Wednesday: Cut out all the cardboard (wood) pieces

Friday: Make the lock for the inner part of the safe using wooden sticks and rubber bands

Tuesday: Glue the rest of the materials together, to make a proper rectangular shape of the safe.

Thursday: Identify and improve on problems



Science and Engineering project – Define and Inquire

Purpose of the Project

We are required to use the scientific idea of energy transfer and create a project that is usable, effective, and purposeful.


1. Cardboard Wind Turbine

I discovered that many people are doing this, so I thought it would be better to have more diversity.

2. Cardboard Combination Lock

This lock, unfortunately, did not use any method of energy transfers, so I searched for similar projects.

4. Cardboard Combination Lock

This is another combination lock I found that uses elastic potential energy.

Difficulties: The process of making it is a little complicated considering the limited time provided. Also, measurements and gluing need to be very precise in order for the lock to work and open.

3. Safe that unlocks with Card

The safe is kind of similar to the previous idea: the lock combination. However, this safe requires a shorter time to make, so I’ve decided to make this safe for my engineering project.

Audience: The target audiences are people who lose things easily

Purpose: It’s to store objects and prevent from losing small but valuable items.

Energy transfer: elastic potential energy – kinetic energy. The inside structure of this safe use the rubber bands to lock and unlock the door of the safe.

Changes: I will be changing the materials and structure of the safe to make it more secure. Since cardboard can be easily destroyed or harmed I will use wood to make this safe.