def METHOD_NAME(self, element_name):
    self.init_NIST()
    # return if already exist
    if element_name in self.g4_elements.keys():
        return self.g4_elements[element_name]
    # we build and store the G4 element if not
    if element_name in self.nist_element_names:
        be = self.g4_NistManager.METHOD_NAME(element_name)
        self.g4_elements[element_name] = be
        return be
    if element_name not in self.element_builders:
        gate.fatal(f'Cannot find nor build element named "{element_name}"')
    be = self.element_builders[element_name].build()
    self.g4_elements[element_name] = be
    return be