A good example how a borescope can be used in building industry.
Sometimes it is necessary to check for mold inside building constructions.
Where a 2" diameter hole is not permitted, we may explore using this small borescope which requires a hole about the diameter of a pencil. Often this probe can be inserted behind loose trim or in existing building openings to permit a limited-access view of building cavities without any destructive cuts at all.
You can shop, or find additional information on borescopes here.