database design

A piano manufacturer employs piano technicians who inspect instruments before they are shipped to custome . When inspecting an instrument, Technicians apply specific Inspection Tests; more than one Test can be applied for an inspection. Each piano is inspected by at least one technician, and a technician can inspe more than one instrument. Inspection Test has a Test Number and Description. Some Tests are combinations of other Tests; a particular Test can be included in multiple combined Tests. Technicians are described by Employee ID and Name. .Each instrument has a unique Instrument ID, manufacturing date, and instrument brand. For each inspection by a technician using a specific Test we need to keep in the database the date of inspection and evaluation grade