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Objective: Use any phone case to mold a brand new carbon fiber composite case for the same model

Hazards: Use proper lab safety techniques to prevent avoidable hazards. Carbon fiber frays easily and can cause skin irritation upon exposure. Uncured epoxy can also cause skin/eye irritation and must be disposed of properly in a separate contaminant bin. Dremmel tool and attachments may not be secured properly or may cause injury due to sharp blades/bits.

Step 1: Gather Materials

To properly complete this build, you'll need:

Safety/General Components

  • Vinyl Gloves
  • Nitrile Gloves
  • Eye Protection
  • Face Mask
  • Plastic Wrap
  • Paper Towel
  • Phone Case
  • Wax Paper
  • Masking Tape
  • Carbon Fiber Sheet
  • Fiberglass Scissors / Kevlar Shears
  • Disposal Container
  • Vacuum Bag
  • Vacuum Bag Nozzle
  • Dremmel Tool

Plaster Production

  • Plaster Powder
  • Water
  • Craft Stick(s)
  • 16 oz. Plastic Cup(s)
  • 3 oz. Paper Cup(s)

Epoxy Production

  • 3 oz. Paper Cup(s)
  • Craft Stick(s)
  • Fibreglast 2000 A Epoxy Resin
  • Fibreglast 2120 B Hardener (2 Hour Cure)
  • Foam Paintbrush(es)

Step 2: Prepare Work Station

  1. Put on safety glasses
  2. Put on vinyl gloves
    • Other gloves may suffice, but make sure they are appropriate for the chemicals being used. Reference a Chemical Resistance Chart if unsure of compatibility
  3. Cut out a 3x2' area of plastic wrap and cover workspace
    • Apply masking tape to edges to prevent movement during work
  4. Select desired phone case
    • Case must have hard shell on inside of phone and cannot have dimples or "honeycomb" structure as this will affect the molding process and vacuum bagging procedures
  5. Use soap and water to clean phone case, removing dirt and various particulates
    • Dry using paper towel or cloth to remove excess water

Step 3: Prepare Plaster

  1. Read proper ratios of plaster mix to water and follow instructions on ingredient containers
    • All following measurements were provided by the specific company
  2. In large plastic solo cup, measure out 1/3-1/2 a cup of plaster mix
  3. Use separate cup to measure appropriate volume of water in 2:1 plaster to water ratio
    • Measuring into the same cup may cause a premature reaction or improper ratios
  4. Add water to large plastic cup with plaster powder slowly
  5. Mix with craft stick until homogeneous, being careful to not aerate the plaster with unregulated mixing rates
  6. Plaster is properly mixed when all "chunks" of plaster mix have been dissolved within the mixture

Step 4: Create Phone Case Mold

  1. Line phone case with adhesive side of wax paper
    • Use finger or crafting stick to smooth edges and coat inside corners for complete seal
    • Any wrinkles or imperfections in this step will continue in your mold/case throughout the process
    • It is okay if camera/charging holes are covered in this step, as they will be defined in Step 10.
  2. Place phone on plastic wrap workspace
  3. From cup, pour mixed plaster into case slowly, using stick to flow into case in a controlled manner
  4. Move cup from left to right, across the case, to not have any buildup or "mountainous" regions of plaster buildup.
    • Use crafting stick to smooth out regions or remove excess plaster
  5. Let plaster set for 24 hours in undisturbed location
  6. When set, pop out of phone case, being careful not to chip edges
    • Use a crafting stick or similar blunt object to file down imperfections

Step 5: Cut Sheet of Carbon Fiber

  1. Measure dimensions of phone case (as if wrapping a package)
    • Leave room to cover to other side of phone case by approximately 2 cm in each direction as seen in the attached image
  2. Outline desired sheet size with masking tape
    • This will prevent the carbon fiber from immediately fraying upon cutting. The tape will eventually be cut off of the case with other excess material
  3. Use fiberglass scissors / Kevlar shears to cut to proper size.

Step 6: Wrap Your Plaster Mold

  1. Place fiber under phone case with the "exterior" of the plaster facing down and the "screen" side face up.
  2. Fold edges over until corners collide and follow Option 1) OR Option 2)
    • 1) Cut the sheet at 45 degree angle to corner, creating two small edges that can be tucked under each other to create a flat, tight corner
    • 2) Take short edge corners and fold inward to form trapezoid shape. Then flip over plaster to finish the edge
  3. Tape folded edges to plaster
    • Make sure tape only touches plaster and other tape/removable areas
    • After epoxy coating, tape can only be removed by cutting off the entire section

Step 7: Make Epoxy Coating

  1. Put on nitrile gloves
  2. In paper cup, mix 3 parts 2120 B Hardener to 1 part 2000 A Epoxy Resin by volume
    • Depending on your hardener (this is for a 2 hour cure), follow the appropriate instructions listed on your hardener label
    • Stir using stick until it appears homogeneous and all discolored "striations" dissolve into the epoxy
    • Be sure to put proper lids on A and B components, as mixing them will harden them to the container and it will be difficult to reopen/use in the future
  3. Dispose of all uncured epoxy contaminated materials in disposal container

Step 8: Apply and Seal Coating

  1. Using foam paintbrush, apply thick layer of carbon fiber over phone case
    • Apply thicker coat to corners and edges of phone case, as a thin layer will peel off over time due to the epoxy settling at the bottom
  2. Place phone case exposed-plaster side down into vacuum bag
    • Keep approximately 5" from vacuum nozzle as the pressure and height of nozzle will cause epoxy pooling if multiple are being done simultaneously
    • Each phone case should be approximately 1" apart in each direction
  3. Seal bag by removing adhesive putty and lining edges between plastic sheets
    • Press from center of strip outward to minimize misalignment of the bag edges
  4. Attach nozzle to vacuum pump and keep active until epoxy cures (~2 hours)

Step 9: Remove Plaster and Clean Case

  1. Remove case from vacuum bag
  2. Crack plaster to remove from case
    • Using hammer, crack the face of the plaster and remove large pieces
    • Any small pieces can be removed by angling a large-based screwdriver into plaster and tapping end with hammer
  3. WARNING: Improper chiseling technique can leave holes in case
  4. Use tap water to remove any particles residing on surface

Step 10: Create Phone Specific Modifications

  1. Using Dremmel tool and cutting blade on medium setting, carefully remove excess carbon fiber and cut to proper dimensions
  2. Change to boring bit to drill holes in the material that matches the camera hole locations on the phone
    • Apply in center of region and slowly push down widening the hole and polishing the edges
  3. Use sanding bit or small boring bit to remove loose/uneven fibers from the case

Step 11: Apply Final Layer of Epoxy

  1. Create epoxy using procedure from Step #7
  2. Using foam paintbrush, coat phone case in epoxy, ensuring to get inside corners
    • Small holes may be sealed by the epoxy, but after curing they can be opened/widened by a toothpick, pencil, or Dremmel
  3. Place on plastic wrap to cure for 2 hours
  4. When done, wash with soap to remove any excess material or coatings
  5. Celebrate your new accomplishment

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