Disclosed herein, amongst other things, is a method for converting a design of an original preform that is blow moldable to form a container into a converted preform having less molding material that is blow moldable to form the same container. The method includes retaining a neck finish and body of the original preform on the converted preform. The method further includes replacing the original base of the original preform with a converted base having an outer base surface that joins with an outer body surface of the body at an base split-line of the original base and that fits offset within an outer body surface of the original base, whereby the converted preform has a reduced total length, disregarding any gate vestige that may be formed thereon, relative to a total length of the original preform.