Final answer:
A homemade instrument like a gourd banjo or a cigar box guitar would not have been the featured soloist in a classical-period solo concerto.
Step-by-step explanation:
In a classical-period solo concerto, the featured soloist is typically a virtuoso performer on an instrument that can project and maintain its prominence against the accompanying orchestra. Instruments commonly featured as soloists in a classical-period solo concerto include the piano, violin, cello, flute, clarinet, oboe, trumpet, and horn, among others. However, a homemade instrument like a gourd banjo or a cigar box guitar would not have been the featured soloist in a classical-period solo concerto, as these instruments were not commonly used in classical music during that time.