How to Build Your Own Fiberglass Car Body

Written by alex zang
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If you've ever watched a soap box derby, you've probably noticed a wide variety of materials being used -- wood, simple metals, and more frequently, fibreglass. While wood and metal both require a drawn design to be properly put together, fibreglass only requires a mould. You can build this mould yourself or purchase one off of the Internet. Once you have the mould, you can build your own fibreglass car body, one fully capable of competing in a soap box derby.

Skill level:

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Things you need

  • Car mould
  • Car soap
  • Water
  • Car wax
  • Rag
  • Paint brush
  • Gel coat
  • Resin
  • Hardening agent
  • Spreader
  • Sabre saw
  • Sandpaper

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  1. 1

    Clean any dirt or grime off of your car mould using a combination of car soap and water.

  2. 2

    Use a rag to rub car wax onto the mould using a circular motion. The car wax is what will help you remove the fibreglass from the mould, so it's better to apply at least two layers.

  3. 3

    Use a paint brush to apply a layer of gel coat onto the mould. Gel coat comes in a variety of different colours and helps protect the fibreglass from moisture.

  4. 4

    Lay sheets of fibreglass on top of the mould. Use clamps to hold the fibreglass to the mould. Ideally, you want to have every area of the mould covered with mats of fibreglass. Leave some overlap between the fibreglass mats as they will shrink once you've applied resin.

  5. 5

    Mix a hardening agent with your resin according to the instructions that come with the resin. Make sure you're wearing a respirator and working in a well-ventilated area, as the fumes from the resin can be harmful to your lungs.

  6. 6

    Lift a small segment of fibreglass up and apply the resin to the mould beneath it with the brush. Do this for every sheet of fibreglass on your mould.

  7. 7

    Press the sheets back onto the mould, then apply resin to the top of the fibreglass. Brush resin over the mats of fibreglass until all of the individual fibres have disappeared and the fibreglass has moulded.

  8. 8

    Run a spreader over top of the fibreglass to remove any air bubbles. While small, air bubbles can harm the integrity of the fibreglass, weakening it. Allow the fibreglass to cure.

  9. 9

    Lay another layer of fibreglass on top of the first, then repeat steps seven and eight. Again, allow the fibreglass to cure.

  10. 10

    Cut off excess fibreglass by using a sabre saw. Sand down the sharp edges with sand paper.

  11. 11

    Paint another layer of gel coat on top of the cured fibreglass. Whatever colour of gel coat you choose, this is the colour your fibreglass body will be. After the first layer has set (about two or three hours), paint on another layer.

  12. 12

    Remove the fibreglass car body from the mould. This may be as simple as pulling the body off of the mould, or you may have to break apart the mould and remove it piece by piece.

Tips and warnings

  • You may want to add additional layers of fibreglass over top of any seams for extra strength.

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