3D Printed Phone Case

I am a very clumsy guy. My phone regularly slips out of my pocket or falls down from my desk. Because of the constant dropping, my phone broke case several times. I procrastinated fixing it and just taped it back together several times. However, the tape was not very effective, and the phone case started falling apart again, so I decided to design and print my own custom phone case.

This was a project I did for my engineering class, and I would like to thank my teacher, Ms. Berbawy, for helping me with this awesome and challenging project.

• NinjaFlex Filament
• 3D Printer (Lulzbot Taz 6)*
• 3D Modeling Software (Fusion 360)*
• Slicer (Lulzbot Cura)*
• Calipers
• Pliers
• X-Acto Knife or Box Cutters

*These are what I used, you can use another software or hardware that you are familiar with.

I needed to know my phone's correct dimensions and where the features of my phone were in order to design a functional case.

I first searched for the dimensions of my phone online to see what the official specs were and because the phone has many rounded features that are difficult to measure with calipers. My phone is an Honor 20, and I could only find the basic dimensions (width, length, height) from the Honor's official website (specs page for Honor 20). My phone is not too mainstream, so it took a while to find.

Since I couldn't find detailed dimensions online, I used dial calipers to get my own accurate dimensions. I basically just used the calipers to find the dimensions and positioning for the smaller features on my phone, such as the power/volume buttons, the charging ports, and the speaker sizes. I referenced the position of my features with edges of the phone. For the curves and fillets, I made an educated guess with my calipers.

This first model wasn't necessarily super accurate. It was more of a base for reference when designing the basic phone case.

Using the dimensions that I measured, I started modeling my phone in Fusion 360.

I first modeled the basic shape (right rectangular prism) by using the dimensions I found on the official website for my phone. Then, I filleted the edges based on estimates I got with my calipers. After that, I added the rest of the features I had measured, doing the best job I could.

At this point, I created a CAD model of my phone in Fusion to help me make a better phone case. For instance, I could create a assembly of the phone and case to see if they would really fit together.

My first prototype didn't quite fit my phone. I expected this. First prints rarely work out, which is what prototyping is for.

At this point, I imported the file of my phone into the phone case file and designed my phone case around it.

To create the bumper around the phone, I followed this video (2:05) to help model a basic structure around the phone using a sweep.

I had to create holes in my phone case in order for these functions on my phone to work with my phone case.

• Power Button
• Volume Button
• Speakers
• Microphone
• Fingerprint Sensor
• Cameras
• Flashlight
• Charging Port

I projected the reversed engineered phone's features into sketches on the phone case. I then offset a shape from that projected geometry for all the features.

For the volume button, I did a cover instead of a hole. I just made a bump with a shell on the inside, so the volume button can fit snugly while being protected by the case.

For the charging port, I made the hole 7 by 6 mm because the tip of my charger or headphone jacks were not limited to the size of the phone's female connector.

I printed the case in NinjaFlex, which is a speical TPU made by NinjaTek and is a type of flexible filament. I printed on the Lulzbot Taz 6 fitted with an Aerostruder.

These are my slicer settings.

For the first time printing I didn't use any supports, which made the print really droopy. After that I used supports, even though NinjaFlex supports are difficult to remove. I had to use box cutters and pliers to removed the supports.

For those not using a Taz 6 and want to try printing at home, here are some videos I found while researching and testing with different print settings. So if you're having any issues printing with ninjaflex, they might be helpful to reference.

After printing the first prototype, I tried it on my phone. As expected, it didn't work as well as I thought it would. All the features of the phone case weren't aligned with the phone's features. So I had to use my calipers and measure the offset between the case and the phone's features and make changes in the CAD file. This printing and adjustment process took a long time and a few iterations, especially because the print sometimes failed.

Even though Fusion has it's own versioning process, I created my own new files after every successful print in order to keep track of my process and not corrupt any "successful" print files. In addition, this helped with the version control in a way since the versions weren't just in one single file, which would have made it very confusing and easy to accidentally delete or corrupt the progress I made.

After creating an usable phone case, I was able to print a phone case in my favorite color, black.

I also considered created another phone case with a custom model like the one in this video. However, after much consideration, I don't think it would've been to successful since ninjaflex is difficult to work with, especially when creating complicated structures like this. The drooping would've driven me crazy. Another variable, was that the phone case would be less protective than I would want it to. And since I'm a clumsy person, I didn't want to sacrifice the protection for a custom design.

I also considered printing sticker of my favorite game character to put onto my phone.

I had a lot of fun and gained a lot of experience from this project. The phone case was pretty durable and works pretty well. I hope you can also learn something from this and create your own phone case.