Introduction: DIY Cardboard Smartphone Film Scanner

Build a smartphone film scanner using cardboard and an old flashlight. It's a convenient and easy way to digitalize and scan your old 35mm film negatives using just a smartphone ans some office supplies. Easily share them instantly on social media (via Instagram, Facebook & etc..)

My Official Video Tutorial (TechBuilder - ASCAS):

My Original Classic From 2012:

This tutorial is my modern take on my classic film scanner project back in 2012. It uses a similar design. Several improvements were implemented on my current version to make the materials more accessible and doable for kids and inexperienced enthusiasts.

Step 1: How It Works?

Before digital cameras, images were stored in film negatives. These negatives are photos with negatively inverted colors. If you've played around camera filters on your phone's camera app, Instagram or Snapchat; you can place your negative in front of a light source and as you take a pic with a "Negative/ Inverted" filter, you will end up seeing your film come to life. This project acts as a well diffused backlight equipped with a feed guide to make the scanning process more convenient.

Step 2: Tools & Materials


- Foam Board - LED Flashlight

- 9V Battery & Clip

- White Plexiglass/ Acrylic Diffuser

- Toggle Switch

- 100 Ohm Resistor


- Gluegun

- Cutter Knife

- Soldering Iron

- Desoldering Pump

- Lead

Step 3: Measuring Flange Distance

Before building your scanner's enclosure you must determine your smartphone's flange distance. What is a flange distance? It is your phone's ability to focus on objects at the closest possible proximity. This can be done by printing texts or images on a piece of paper and try to move your phone up and down as it tries to focus on the texts. Use a ruler to take the distance of your phone's camera to the text. Once it focuses well, take note of that measured distance.

TIP: After finding the closest distance your phone can focus on, add a few mm/in of margin to prevent focusing problems once you finish building the enclosure.

Step 4: Foamboard Cutouts

Let's now build the scanner's enclosure. Grab a cutter, ruler and a cutting board and start cutting out these foamboard cutouts based from the flange distance I took from my Vivo V11. These measurements work with most smartphones.

Side Panels: 70x65mm (2x)

Front & Rear Panels: 120x65mm (2x)

Other Panels: 130x70mm (3x)

Step 5: Building the Box

Use your glue gun to assemble your foamboard cutouts. In this step is too vague, watch my video tutorial at (2:00). You can use an edged box as a jig to help you with the angles of the panel's construction.

Step 6: Cutting a Camera Hole

Use your cutter to cut a rectangular hole for your phone's camera to see through.

Step 7: Cutting the Plexiglass Diffuser

Grab a hacksaw and cut a 40x45mm rectangular piece from a white translucent sheet of plexiglass/ acrylic/ polycarbonate. Locate the center of one of the 130x70mm foamboard cutout and use your plexiglass as a stencil. Then use a cutter to cut a rectangular hole through the foamboard.

Step 8: Gluing the Plexiglass Diffuser

Pop the plexiglass diffuser right in your foamboard's rectangular hole from the center. Use hotglue to hold it in place.

Step 9: What's the Plexiglass Diffuser For?

The plexiglass acts as a diffuser to create an evenly lit backlight for your film scanner. At this point you can play around with it by placing a lamp or any kind of light source at the back of your assembled diffuser panel. Running a film through it should provide an evenly lit view of your film negative.

Step 10: Adding Film Feed Guide Rails

Cut a long and narrow rectangular strip of foamboard as your film's feed guide. This prevents your film from moving sideways as you feed it in your scanner.

Step 11: Recycling LEDs From an Old Flashlight

I have a ton of broken flashlights lying around, I suspect it's only the switch that is broken. I took it apart and used a desoldering pump and a soldering iron to remove the solder tin to dismount the LEDs from the PCB.

Step 12: Building a Secondary Diffuser Using Bendy Straws

Cut at least three strips of white translucent bendy straws and hotglue it in three evenly distanced areas on your diffused panel.

Step 13: Bendy Straw Tube Diffuser Concept

The idea is to shrink the film scanner's form factor by refracting the LEDs light rays perpendicular to the main diffuser using some bendy straws. This acts as a secondary diffuser to make light spread more evenly on the main plexiglass diffuser.

Step 14: Wire and Solder the Components

Solder the components in place by following the schematic diagram that I have provided. LEDs consume around 3v per bulb. Since we are using a 9v battery as our power source, we need to connect three of them in series. Since each bendy straws require LEDs on both sides, both series combinations must be connected in parallel to properly power 6 LEDs. A resistor is required to limit the current flowing through the simple circuit.

Step 15: Installing the Batteries

Since I lacked a 9v battery clip at the time, I decided to hotglue the 9v battery in place on top and across the feed guide rails.

Step 16: Adding a Base Plate

To prevent the film scanner's LED tubes from getting mushed, I decided to cut and glue two layers of foamboard as feet and hotglued a 130x70mm foamboard panel as a base plate.

Step 17: Download These Film Scanner Phone Apps

There are many available phone apps that you can use to invert negative images to positives. My favorite is Negative Image (by: KADA Studios).

Phone Apps:

- KODAK Mobile Film Scanner (by: KODAK -

- Negative Image (by: KADA Studios -

- Photo Negative Scanner (by: Appdictive -

- HELMUT Film Scanner (by: -

Step 18: Enjoy!

Turn on your film scanner's switch, feed in a film negative, your phone app, take a pic, the app does the rest.


Step 19: Instagram!

If you like this project, feel free to check out my Instagram account for my travel photos.

INSTAGRAM: @AngeloCasi ( )

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