Repairing Fiberglass body parts for racecars is a chore that sometimes needs to be completed in short order.
Basic tools, resin, and PPE (gloves and glasses) will allow for a professional-quality repair. Practice and experience will help these types of repairs to appear and function in a much more professional manner. These materials are very science-based, and details matter.
Thanks to Tim McAmis Performance Parts for describing this process.