Converting a hardtop vehicle to a convertible primarily involves cutting the existing hardtop roof from the vehicle and installing a convertible top. However, convertible conversions are extremely complex in many cars due to the load-bearing functions of the car's roof and the need to fit the convertible top in the car's existing structure. It is often necessary to add considerable amounts of structural reinforcement and chassis modification to make a functional and safe convertible from an existing hardtop car.
The complexity of successfully converting an existing hardtop car to a convertible makes it a daunting task for most amateur mechanics, as do the extensive amount of tools and materials required. Cutting the existing hardtop from the vehicle requires metal-cutting tools, while attaching new structural reinforcements and chassis modifications requires welding equipment and additional metalworking gear.
In addition, electrical system expertise is often required to re-route any electrical conduits that may have run through the vehicle's roof and to install any electrical systems that may be required by the new convertible top. Car owners interested in converting their hardtop vehicles to convertibles engage the services of dedicated coachbuilt convertible conversion companies due to these issues. However, some companies do sell parts and kits for converting some models of cars to convertibles for do-it-yourself mechanics.