Thin flat surfaces of the plastic parts are weak like top and bottom of the plastic containers and air tight jars. To give them desired strength there is a top as well as bottom treatment given to those parts. The top treatment may involve a kind of corrugation over the top. These corrugations not only provide the strength but also act as a locator for the other parts during stacking. There are small protrusions at the bottom. This thick element is acting like a rib providing the desired strength to the part. This element at the bottom also prevents the bottom surface to come in direct contact with the rough surface which may cause scratches. A special type of these protrusions may also contain some rubber pads which will provide a proper grip to the product with ground. Corrugation at the bottom of the PET bottles provides both strength as well as stability to the bottle.