This Instructable will be a step-by-step guide on making a phone case using carbon fiber reinforced polymer (CFRP).
Before getting started, you will need to prepare the following:
- Clear, flat tabletop with saran wrap taped down on top
- Area should be available for at least 60 hours to allow for plaster hardening and epoxy curing
- Cell phone case
- Saran wrap
- Dry mix plaster and water
- Paper or plastic cup
- Sand paper
- Vinyl gloves
- Carbon fiber fabric
- Epoxy resin
- Epoxy hardener
- Nitrile gloves
- Lab coat or full length clothing
- Paper or plastic cups
- Wax paper
- Sponge paint brushes
- Vacuum bag
- Double-sided tape
- Vacuum pump
Step 1: Preparing Your Workspace
This tutorial requires the use of a clear, open tabletop with saran wrap laid down and taped on the sides to help deal with spills from epoxy. This project will take several days in its entirety to allow for plaster and epoxy to dry, so it is important to use a space that will be accessible and clear from any interference with your work for a few days (i.e. don't use your kitchen table if you plan on using it in the next few days).
Step 2: Making a Plaster Phone Mold
- Take case off your phone and clean with soap and water to remove oils. Dry completely.
- Place layer of plastic wrap inside case and tape so that it conforms to the interior and allow it to wrap around to the back of the phone case. It is important to press down the inner corners well to achieve a high quality mold. Tape down on the back side so that the tape does not touch the inside of the case.
- Using a paper cup, mix plaster and water according to the directions on the container. Different brands may have different specifications, though in this case, it was a 2:1 plaster to water ratio. Be sure to add the water into the plaster SLOWLY.
- Pour plaster into the case mold. It may be helpful to poke holes outward through areas that you want to cut out later such as the holes for the camera or headphone jack. Allow to dry overnight.
- Once the plaster is dry, remove it from the phone case and sand down any areas (using sand paper or even popsicle sticks) that are rough or do not conform to the cell phone case dimensions. Do not sand too much from the sides, or else the final phone case will be too small to fit your phone.
Step 3: Mold and Carbon Fiber Sheet Preparation
- Place a sheet of wax paper onto the back side of the phone mold. Wrap it over the sides and tape down on the front side of the mold in the center.
- Cut a piece of carbon fiber fabric, allowing for 1/4-inch to wrap over the front face of the phone mold.
- Attach fabric to the mold with masking tape in the same way as step #1 (tape on front). Avoid placing tape in areas that will be part of the case, as tape will stick to epoxy. It is fine to have tape in the center because excess carbon fiber can be removed at the end.
Step 4: Carbon Fiber Layup
Be sure to wear goggles and nitrile gloves for this step.
- Mix epoxy resin with hardener in a ratio according to the directions on the container, avoiding air bubbles. I used System 2000 epoxy which required a 3:1 resin to hardener ratio.
- Apply epoxy to the carbon fiber layer on the front and back of the mold. Use generously to create a tacky surface.
Step 5: Vacuum Bagging
- Prepare vacuum bag by cutting a section to size with a little extra room for the vacuum pump tubing. Seal one side using double-sided tape.
- Cut hole in top of vacuum bag to insert vacuum tubing.
- Place phone mold in vacuum bag and use double-sided tape to seal other side.
- Turn on vacuum pump and remove air bubbles.
- Allow pump to run for 2 hours.
- Leave phone case in bag for 24 hours to allow the epoxy to dry.
Step 6: Remove Phone Mold and Begin Cutting Phone Case to Shape
- Remove phone mold from vacuum bag once it is dry.
- Use a Dremel tool with a blade to cut out a rectangular section from the front of the phone case where the phone screen would be.
- Use a hammer, screwdriver, and tweezers to remove the plaster mold and wax paper.
Step 7: Cut Out Details of Phone Case
Use vinyl gloves, goggles, and full-length clothing for this step.
- Use a Dremel tool to cut out smaller holes such as the areas for the camera, charging port, and headphone jack.
- Use a Dremel polishing tools to smooth edges. Avoid skin contact with any dust produced during this step, as small carbon fibers may penetrate the skin and cause irritation.
- Once all the holes are cut out, paint a final layer of epoxy on the phone case and allow it to dry overnight.
- After the epoxy has dried, the phone case is ready to go!