Introduction: How to Make a Carbon Fiber Cell Phone Case

Image 1: Carbon fiber cell phone case as it might look when you finish

In today's age of advanced electronics, smartphones are have become ubiquitous. Equally as ubiquitous, is the cell phone case - used to protect the smartphone from damage as well as to add a unique styling to a mass-produced model. This instructable serves as a guide to creating your own cell phone case for your smartphone with the sleek look of a carbon fiber weave.

What you will need for this project:
Disposable gloves of some sort (we used vinyl gloves) and goggles
A cell phone case that fits your smartphone
A plaster mix (we used DAP Plaster of Paris Professional Quality)
Saran wrap or something similar (we used Glad Press'n Seal)
A carbon fiber weave (we used Fibreglast 3k 2x2 Twill)
Epoxy resin and hardener to help adhere the epoxy to the carbon fiber weave (we used Fibregast 2000 Resin & Fibreglast 2120 2 hour epoxy cure)
A vacuum bag
Epoxy resin and hardener to act as a glossy finish to the carbon fiber weave (we used TAP General Purpose Epoxy Resin & TAP General Purpose Epoxy Hardener)
Cheap, disposable paint brushes
Wooden sticks
A good pair of scissors
A sanding machine
A screwdriver
Duct tape

A few general tips before we get started:
Stray carbon fibers can be surprisingly sharp, handle them with care to avoid cuts
Try and work in a well-ventilated area, as the epoxy can have a bad chemical smell

Step 1: Making the Mold

Image 1: Your current cell phone case wrapped in plastic to protect it from the plaster
Image 2: The plaster that we used for this project
Image 3: What your final mold should look like

The first thing that you'll want to do when making the mold is to apply the saran wrap to your cell phone case. Make sure that you cut more than enough saran wrap to the entire cell phone case sufficiently. Use your fingers or a wooden stick to try and get the saran wrap to stick to the edges of the cell phone case well. Making sure that it sticks well to the edges is key to making sure that you get a properly sized mold to fit your cell phone case. If your cell phone case has holes in it for headphone jacks or charging ports, make sure that you get the saran wrap to match these curve and holes.

After this, you'll want to prepare your plaster as described by the instructions provided with the casing. Once mixed, pour the plaster onto your saran wrap casing. Take care not to pour too much, but remember that if you have a sanding machine, you can shed plaster later. Use a wooden stick to try and get the plaster at an even level throughout the wrap. Let the mold sit and properly form before proceeding any further.

Finally, you will want to remove the plaster and the saran wrap and your phone case from one another. Sand the plaster to get rid of any rough edges.

Step 2: Cutting Out the Carbon Fiber

Image 1: Carbon fiber cut around the mold

Now that you have finished sanding the plaster, it is time to cut out of the carbon fiber weave to get the base for your cell phone case.

Place your cell phone plaster on a sheet of carbon fiber. Place tape on the carbon fiber around the area of your phone plaster. Ideally, you should give more room then displayed in the picture, but this is a good idea in general of what you want to do. Next, cut through the carbon fiber along the center of the tape - using a strong pair of scissors as carbon fiber is quite difficult to cut. There should be enough carbon fiber here to wrap around the cell phone plaster the same way that a phone case would wrap around a smartphone.

Step 3: Mixing the Epoxy

Image 1: The line of products for the epoxy we used - Fiberglast System 2000 Epoxy Resin.

Once the carbon fiber weave has been matched with the plaster, it is time to mix the epoxy. Epoxies usually come in two parts - a resin and a hardener. Mixing them correctly and effectively will require very specific steps to be done to ensure the epoxy is formed correctly and is done safely. If you've never worked with epoxy before, please read the following paragraph carefully for a few pieces of information.

Epoxies have what is known as a "setting time". This means that the epoxy will transition from a viscous mix to an adherent as the resin and hardener chemically react. In order for you to apply the epoxy correctly, you will have to apply it before it sets. Epoxies also release a good deal of heat in what is known as an exothermic (heat generating) reaction upon setting, so whatever containers you use to mix the epoxy in will have to be properly disposed of once you are done applying it. For this same reason, it is also crucial that you use only mix a sufficient amount of epoxy - as more leftovers will produce more heat. Finally, how you mix an epoxy will drastically alter its properties. Too much hardener will make the epoxy very brittle, and bad mixng will not allow the resin and hardener react correctly.

Keeping all this in mind, realize that very soon after you mix the epoxy, you should proceed to the next step of applying it.

Wearing your gloves, pour the epoxy resin into one cup and the epoxy hardener into another cup. Make sure that you pour them out in proportions as recommended by the brand of epoxy that you are using. A 1 to 1 epoxy resin to hardener proportion will require you to pour out an equal amount of resin and hardener. Take note if the proportion is based on weight or volume as volume will be easy to match with a simple examination, but a weight proportion will require a scale of some sort to do the job properly. After pouring each into each cup, pour each into a third, much larger cup, to mix them in. Use a wooden stick and mix the epoxy. Try and use a folding mixing technique similar to how you would mix a souffle. Do not mix too fast, or else an excess of bubbles will form. Mix for however long your brand recommends) before getting out the paintbrush.

Image: Fibreglast, Fibreglast System 2000 Epoxy Resin. Undated.

Step 4: Applying the Epoxy & Vacuum Bagging

Image 1: Carbon fiber cell phone case in a vacuum bag, with carbon fiber taped around the mold.

Apply the epoxy with the paintbrush to the carbon fiber weave, wrap the edges around the phone plaster, and tape them down to the phone. This will allow the carbon fiber to get a good shape with the epoxy.

After doing this, put the carbon fiber-epoxy-plaster into the vacuum bag. Let the vacuum suck out any bubbles in the epoxy and let the epoxy dry in the vacuum bag. The strength of your vacuum will determine how long you will want to keep the cell phone case inside. In general, 24 hours should be sufficient regardless of the vacuum strength for the epoxy to finish drying and for the vacuum to pull out all the bubbles.

Step 5: Extraction of Plaster & Fiber Trimming

Image 1: Carbon fiber cell phone case after plaster removal

Now that the body of the cell phone case is complete for the most part, it's time to make the case nice and neat. This will involve removing the tape and plaster from the carbon fiber and cutting off stray pieces of carbon fiber before applying the final glossy finish.

First remove the tape by peeling it off. To remove the plaster, get out a hammer and something to concentrate force, such as a screwdriver. Use the hammer to bash the screwdriver and break the mold. Once the mold is broken, it should be fairly simple to remove by pulling out the pieces. To manage stray pieces of carbon fiber, simply use scissors to cut them off. Finally, for any charging or headphone ports, use a sander to drill holes into the casing.

Step 6: Final Glossing

Image 1: Gloss epoxy resin that we used
Image 2: Glass epoxy hardener that we used
Image 3: Application of the gloss to the carbon fiber cellphone case

Once again, you will mix an epoxy and apply it to your carbon fiber cell phone case. This time, however, you will use a different epoxy - one well suited for a glossy finish rather than to keep anything stiff or in place. Quite similarly to the last mixing, you will prepare the hardener and the resin in different cups, only to bring them together to mix them.

Be aware that as this is a different epoxy, it will have a different setting time than the previous epoxy. As a result of this, you may have more or less time to apply the epoxy after mixing and to handle the containers which will once again have the remnants of epoxy resin and hardener undergo a heat-producing reaction. Simply apply the epoxy with the paintbrush to the outside of the case and let it sit overnight. With this, your cell phone is complete, and should be of a quality somewhere around the image in the introduction!