How to Make a DIY Projector
Did you know that you can build a smartphone projector out of everyday objects? Well, you can, and it’s actually really simple.
With this DIY project you can learn about light and optics, plus, you can get your creativity going by using this projector in your next artistic creation.
Overall, this is a fun and educational photography hack that you can do by yourself or with friends or family. And if that wasn’t enough, you’ll also be repurposing home objects contributing to a zero-waste culture.
So, without any more introductions, here’s a step by step guide to a DIY smartphone projector.
Table of Contents
What You Will Need
What you’re going to do is build a box that will direct the light from the screen of your phone towards a magnifying glass, which will then project a blown-up version of the image onto a wall on the other side.
To make this you just need a few simple objects. Some of them are optional, but having them will make the process easier and will get you better results.
- Rectangular cardboard box
- Magnifying glass
- Thick black matte paper (alternatively, brush and paint)
- Tape, normal or double-sided (can be substituted with glue)
- Exacto knife or precision cutter (or scissors)
- Protractor (optional but helpful)
Note on the box: If you have a shoe box, this is the ideal size. If not, just make sure it’s a rectangular box. It should be wide enough to hold your phone, but not much wider than that because you want the light to go forward and not spill out to the sides.
Step 1: Cut the Box
The first thing you’re going to do is to separate the part that will hold the lens. This is because you can adjust the focus by moving the lens closer or further away from the image.
To do this, cut out one of the short sides of the box.
Step 2: Cover the Inside of the Box
Now, you need to darken the inside of the projector. This stops the light from dispersing and reflecting back into the image, thus ensuring better quality.
Ideally, you should do this with thick paper – I used Fabriano. This will also help with the overall stability of your projector, as having one side cut out can make it a little wobbly.
If you prefer, you can also use black paint. Just make sure it’s dry before continuing to avoid getting paint all over you and the other parts of the projector.
Step 3: Place the Lens
On the piece of cardboard that you cut during the first step, draw the contour of the magnifying glass. Then, using the precision knife carefully cut it out.
It’s best to cut a little bit to the inside of the circle you traced so that the magnifying glass will fit tightly and not fall out.
You can unscrew or cut the handle of the magnifying glass if it’s too long to fit. Keep in mind that the size and quality of the glass will impact the sharpness of the projected image.
Step 4: Build a Support for the Lens
To keep the lens standing, it needs to have some support. To create this, cut a strip of the black paper that’s long enough to go around the edges of the rectangle your lens sits inside.
Then fold it around and tape it to the cardboard so it’s no longer a flat surface but a rectangular box of its own.
This will give it stability, especially because you might be moving it back and forward to find the right focus.
Step 5: Place the Mirror
Now that you have the lens ready, let’s work on the other side of the projector.
If you put your phone directly towards the lens, the image will be projected upside down and flipped left to right.
This is because the beams of light travel from the screen to the lens forming a cone. They converge in the magnifying glass and are refracted towards the wall in an inverted cone. In this process, the image gets turned around.
It’s similar to what happens in a photographic camera, which is why DSLRs have mirrors in them to make you see the image in the viewfinder.
So, to correct the image from left to right, all you have to do is place a mirror in between the smartphone and the lens. Place it on the back of the box (opposite to the lens) at a 45-degree angle.
You can use a protractor to know the right angle. If not, then you can get approximate by looking down at the mirror and making sure that you can see the lens.
This is how your projector should be looking at this point with the mirror on one side and the lens in the other:
If you don’t have a mirror, you can skip this step. Just keep in mind that the image will be reversed, so try to avoid images that have any writing in them.
Step 6: Cut Out the Lid
Before you put on the lid, you need to make a hole for your smartphone screen. Place it on the backside so that the phone is above the mirror.
Make sure you measure the size of the screen and not the size of the phone, or it will fall in. If your phone has a full-size screen then make the hole a few millimetres smaller – just enough to hold the phone on top.
Step 7: Finishing Touches
Your homemade projector is nearly done!
Put on the lid on the box and make sure everything is fine. It’s normal that you might have to do some finishing touches because this is crafty work.
Check for any excess paper you need to cut, some spaces or holes you should cover to avoid leaks of light, etc.
Also, depending on the side of the magnifying glass you may have to cut a semicircle in the lid if it covers the lens.
Step 8: Start the Show
That’s it – your homemade projector is ready!
This is how your DIY projector should look when it’s fully assembled. Notice how the front is detached from the rest of the box; that’s for adjusting the focus.
Make sure you disable the sleep mode on your smartphone so that the screen won’t shut off. Then, point the smartphone projector at an empty white wall.
If the image is not very sharp, adjust the focus by moving your DIY lens back and forward. You can also get closer or further away from the wall to find the right spot.
So now, close the curtains and give it a go.
Isn’t it amazing? With just a magnifying glass and a cardboard box, you made your very own smartphone projector.
The theories behind this project go back to the 16th century. Back then, artists used this ‘camera obscura’ as a tool to paint.
You can do this too, just aim your homemade projector onto a piece of paper and start tracing. Another creative idea is to project images onto your subjects on your next photoshoot creating unique light effects.
You can also use it to show photos to your friends or as a movie projector to watch films. The only limit is your imagination.
If you enjoyed this DIY project, you might want to try doing a pinhole camera, or a DIY light-box too. Remember, the idea is to stay crafty and stay creative!