This is an easy, quick and funny project to make a magnetic nightlight out of a surprise egg you can find in surprise chocolates of a famous brand.

I made this project because we ate many chocolate eggs recently. And the plastic eggs have ended up on my desktop in order to be reused, between the LEDs, the magnets, and batteries. It became therefore obvious that I had to make magnetic nightlights with these eggs!

If you live in the US, you will probably have some problems to get these plastic eggs. A first possibility is to find another transparent or semi-transparent case with a similar shape. And I have also designed a case with the same shape, so you can 3D print it and use it just as described below! Find it on my Thingiverse account here .

About this project:

Time spent: 5 minutes.
Money spent: few cents.
Difficulty: ★☆☆☆☆

How it works:

Inside the egg, there is a LED, a battery and a magnet connected in an open loop (no current flowing, the LED is OFF). But when the egg is placed on a ferromagnetic surface the magnet is attracted by the surface, connecting the battery to the LED, and it closes the loop: the current flows and the LED lights up. Below is an animated scheme.

There are 2 magnets in this nightlight. Both are used to stick the nightlight to metallic surfaces, but only one is used as a switch to connect the LED to the battery. Therefore if you rotate the egg of 180°, you can switch the LED ON or OFF.

Below are 2 different methods to make this nightlight:

With basic stuff (steps 1 to 4).
With 3D printed parts to hold the battery, magnet and LED (steps 5 to 7).

Step 1: Materials

You will need:

Tape. If it is transparent it is better, so the light can diffuse through it.
An LED. I have used a bright white LED, 5mm.
A button cell (3V).
2 neodymium magnets. Diameter = 8mm; Height = 4mm.
An egg. You can find it in some surprise chocolate egg of a famous brand.

Step 2: LED & Battery

To connect the LED to the button cell, you need to bend the LED. I have placed the positive side of the battery upside. And I have bent the longer leg of the LED (positive) just like the pictures below:

Once the longer leg was bent, I have placed the LED on the button cell and added a piece of tape to fix them together.

Step 3: Magnet & Battery

Then I have placed the magnet on the other side of the button cell (negative side). I have added another piece of tape so the magnet does not move too much. But I made sure to leave a large part of the magnet without tape, so the magnet and the shorter leg of the LED can connect.

Finally, I have bent the shorter leg of the LED so it overlaps the magnet. But a small offset is needed between the leg and the magnet. When the egg is placed on a metallic surface, the magnet is attracted by the surface, and it connects with the leg which is between the surface and the magnet!

Step 4: Inside the Egg

Then I just placed the battery, the LED and the magnet inside the egg. I have added few pieces of tape again to stick everything together.

On the other side of the egg, I have added another magnet and added some tape to attach it.

Step 5: 3D Printed Parts: Battery Holder

I have also designed 3D printed parts to assemble the button cell, the LED and the magnet together.

Below you can see a gif of how to assemble the pieces. Note that I have used 2 magnets on top of each other because it works better this way.

And here is another gif showing how it works. When the "device" is close to a ferromagnetic surface, the magnets are attracted, they make contact with that LED leg so the current can flow and the LED lights up.

Step 6: 3D Printed Parts: the "blocker"

I have also made what I call a "blocker". It keeps the battery holder in the bottom of the egg, but it leaves a little space so the battery holder can move freely.

I think this blocker is more elegant than using tape or glue because you can remove it easily.

You can find the files on my Thingiverse account here .

Step 7: 3D Printed Parts: Plastic Eggs

As written in the introduction, people living in the US may not know these plastic eggs. So I have also designed some similar eggs that can be 3D print.

You can see above 2 pictures of 3D printed eggs with the light inside, one is green, and the other transparent.

Step 8: Diffuse Light

And here is the last tip: for a better diffusion of the light, you can cut the top of the LED. Just use cutting pliers to cut the lens, but make sure the electrodes of the LED are not damaged.