There are no inspection holes on the Stinson from the factory.  I added five to the fuselage to provide access for later inspections. 

How do you make covers for the inspection rings?

Glue a piece of fabric to a frame. Shrink the fabric with 250 degree heat. Draw 6 1/2″ circles on the fabric, cut out the holes, then attach them over the inspection rings. This happens after the Poly brush goes on. The photos are in reverse order.