  We present the many evolutionary routes that progenitors of bipolar planetary
nebulae (BPNe) can take. Overall, there are about a hundred qualitatively
different evolutionary routes, hence about a hundred qualitatively different
types of BPNe. Within each type there are quantitative differences as well.
Adding the dependence of the appearance on inclination, we find that the number
of different apparent structures of BPN is about equal to, or even larger than
the number of known BPNe and proto-BPNe. Accordingly we argue that every BPN is
a `unique' object in its appearance, but all can be explained within the binary
model paradigm. Therefore, we request a stop to the attaching of adjectives
such as `unique', `peculiar', and `unusual' to BPNe and proto-BPNe, thereby
removing the need to invoke a new model for almost every `unusual' BPN. As a
case study we try to build a binary model for the proto-BPN OH231.8+4.2. In our
preferred model the AGB Mira-type star has a main sequence companion of mass 1
Mo, orbital period of five years, and eccentricity of 0.1.
