How to build a fiberglass body kit

Updated July 20, 2017

Body kits are used to give cars a lowered appearance without having to physically lower your vehicle closer to the ground. A car that is closer to the ground has less drag which could potentially increase fuel economy and usable power. You can make your own fibreglass body kits at home in about two weeks. Although building a fibreglass body kit is simple, working with fibreglass takes a great deal of patience and craftsmanship.

Draw out how you want your pieces to look. Pay special attention to the location of where bolts and screws will be. You can copy the design of existing body kits or design your own. If you choose to make the design completely custom, make sure that it fit flush with the vehicle with all of the screw holes lined up.

Carve a block of foam into the shape you desire. You can use a knife to cut out the large pieces and sand it into the design you would like. Cover the foam in Bondo and allow proper time to dry. Drying can take up to a day. Use 220 grit sandpaper to make the surface nice and smooth.

Spray on polyester primer. It should be thick in consistency and made for moulds. The primer can also take up to a day to dry. Do not rush the drying process to ensure that the primer will not crack. Sand with 180 grit sandpaper and progress to 1000 grit wet sandpaper. Let it sit for 3-4 days while waxing it every day with mould wax. Spray three coats of tooling gel and let it sit until tacky.

Apply the resin on the tacky tooling gel. Separate the fibreglass into small fibrous threads. Lay it on top of the resin. Use a roller or brush to remove air bubbles underneath. Repeat six times for a nice thick body kit. After drying for up to two days, use a razor blade to remove pieces of glass sticking out. Use a wooden mixing stick to gently pry out your piece.


Always wear a mask to keep from breathing in the hazardous fumes. Gloves are also necessary to protect you from the glass and chemicals touching your skin.

Things You'll Need

  • Styrofoam
  • Bondo
  • Sandpaper
  • Polyester Primer
  • Moulding Wax
  • Resin
  • Polyester resin and hardener
  • Plastic mixing cups
  • Brushes
  • Fibreglass roller
  • Fibreglass mat
  • Razor blade
  • Wooden mixing stick
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About the Author

Quyen Tong began writing professionally in 2006 when he launched a nutrition information website named Complex Nutrition. He has graduated from Purdue University with a degree in aeronautical engineering and has submitted technical papers regarding the NextGen project and future flight trajectories for air travel within the United States.