We set out to determine if independent inventors can be considered 'heroes' or 'hobbyists', that is, if they produce the most or the least influential inventions in a product category. We study patented inventions by independent and firm-based inventors by comparing patents along four dimensions: Patent citation impact, detail, scope, and maintenance. Examining 225 tennis racket patents granted in the US between 1981 and 1991, we find that independent inventors are a heterogeneous group who generate inventions that are overrepresented both among the most impactful and the least impactful patents. The metrics we develop provide insight into ex ante identification of the importance of inventions.