How to Make a Mouth Operated Stylus for Your Phone (with 3-D Printing)

A mouth operated stylus can be a great way for someone with limited arm mobility to operate touchscreen devices such as smartphones and tablets. Although commercial devices exist, the costs can be surprisingly high for such a simple device. This Instructable will teach you how to create a mouth operated stylus using only a 3D printer (or borrowing one!) and aluminum foil.

• A 3-D Printer
• Non-toxic filament (such as additive free, colorless PLA)
• Aluminum foil

The first step is to create the model that we are going to use to print. You can use any 3D or design software such as Fusion 360, Blender, or SketchUp.

To keep things simple I used TinkerCAD to create my design. The nice thing about TinkerCAD is that it runs directly from the web browser and doesn't require any additional software to install. It also is incredibly simple to share designs using TinkerCAD. My design is available here:

The first important part of the design is the bite block. The bite block increases control and makes it easier to perform fine tasks. I opted for a simple rounded rectangle shape with a ridge to help keep the stylus from slipping when gripped by the teeth. It's important to avoid any sharp edges on the design as these could accidentally scratch sensitive areas of the mouth like the tongue, cheeks, and lips.

The second important part of the design is the length and diameter of the shaft. The shaft should be light enough to not cause fatigue yet long enough so that the person using the mouth stylus isn't uncomfortable or accidentally rubbing parts of their face against the smart device. For a smartphone mounted at eye-level, I found that the comfortable zone was about 6 inches (15.24cm) away from my face.

The third important part of the design is the tip. Most 3-D printer filament is non-conductive and therefore won't work on the capacitive touchscreens found on most modern smartphones and tablets. Therefore your design will have to incorporate a capacitive tip. Originally I deigned my stylus so that I could insert a piece of folded aluminum foil into the tip, but then I realized it was easier to just wrap the tip in foil.

Feel free to modify and share my design to suit your own needs!

The next step is to find or borrow a 3-D printer. You'll need a design with a large enough build area to incorporate your design. For my stylus I used a Creality Ender 3. If you have trouble finding a 3-D printer, many libraries and schools are beginning to add 3-D printers to their collections. The design I created will fit comfortably on most printers with a 200mmx200mm X and Y build area.

One you've found the right printer, you'll need to choose the right filament. PLA is a special type of plastic made from plants. Other common filaments such as ABS could potentially leach toxic chemicals when placed in the mouth. Because our stylus is going to be in contact with the mouth, you'll need to find a filament that is food safe that doesn't leach toxic chemicals. In general, most PLA filament without any color additives ("natural/colorless PLA") is food safe, but when in doubt check with the manufacturer.

The third step is preparing and printing your design. I used Ultimaker Cura for my "slicer," which is a special program that turns computer generated models into 3-D printer instructions.

My design was able to print without "supports" or "adhesions." If you have an uneven printer bed, you might want to turn on adhesions. If you use a design with a lot of "overhangs" - parts are suspended above the printer bed with nothing directly underneath them - you might want to consider enabling supports.

When printing, you might want to make sure that the first few layers print before leaving your printer to do it's own thing. I've noticed that when a lot of my prints fail, it's usually at this step.

After you've completed the print, it can be tricky to remove the build sometimes. For my design, I've noticed that if you carefully insert the scraper directly underneath the tip and apply direct pressure, the rest of the print tends to pop off fairly easily. Be careful not to snap the shaft of the stylus, which can be somewhat fragile.

Modern touchscreens use capacitive screens, which are designed to resist accidental touches when placed in your pocket. Because of this you'll have to use a conductive non-scratching material to trick the device into thinking you're using a finger.

For my design, I used a simple piece of aluminum foil wrapped around the shaft. Be sure to smooth out any wrinkles to avoid scratching your screen. I did this by pushing the end against a hard countertop.

On most devices, the stylus won't work unless the foil makes contact with the skin. This completes the circuit, which makes the smart device believe that the stylus is a finger. I wrapped the foil so that the skin of my lips touched the edge of the foil.