How to Build a Shell Chair

Styles

• Decide which style of chair you want. The chair's base is typically a metal framework, which you can weld together or borrow from an existing chair. But the shell itself can take any form. Some shell chairs have arms, while others are open on the sides. Shell chairs may be entirely smooth and flat or conform to the shape of a seated person.

Traditional Process

• The original process for building a shell chair relies on large industrial machinery. Chairs from the mid-20th century are typically made of extruded fiberglass, which requires a large machine and an assembly line of workers who add casting material, operate the machine and extract the finished chair shells. While this process is impossible to replicate at home, it is an option for small businesses and furniture manufacturers that wish to produce shell chairs.

Options at Home

• You can build a shell chair at home, including one that resembles an industrially produced fiberglass model. The process involves casting an acrylic or fiberglass resin into a mold. The mold can be made of any material that will withstand the heat of the molten resin and be removable once the resin has cooled. For example, a large plaster block, carved to the shape of the chair shell, can serve as a mold for several shells before it will begin to deteriorate. The type of material you use will determine how long it takes to air-dry, along with the appropriate temperature range for casting. Be sure to follow safety procedures for the material you work with, since fiberglass and other resins can be harmful if you breathe their fumes or let them contact your skin.

Finishing

• Once you have a plastic or fiberglass chair shell from your mold, you can turn it into a finished chair. This involves sanding and cutting away excess material left behind from the casting process, as well as adding a layer of clear or colored sealant to protect the surface. You can also add pigment to the liquid cast for a chair that is already colored. Bolts or screws can attach your shell to a metal base, which determines the angle and height of the finished shell chair.