A flexible, one-piece molded plastic closure having a circular outer rim and a center panel. The center panel has thin panel portions bounded by radially extending rib portions, the panel portions and the rib portions being integrally joined to the outer rim.
The method of molding the closure and tooling used therefor are also disclosed. During the molding of a closure, molten plastic flows radially along channels formed in the tooling to chamber portions forming the rim. Plastic remaining in the channels cools to form the ribs. The panel parts between the ribs are formed from plastic flowing from the channels.