Eh? You can make legless creatures. Example:Pyro Paul post=9.69724.670931 said:yes, with enough patience and skill you can eventually replecate Some real life animals. however the limitations of the game often makes it impossible to create creatures which acctually exist.
you can not make animals which use their hands for support (gorillas)
you can not make asymetrical animals (fiddler crabs)
you can not make legless creatures (worms)
it is very difficult to make small creatures (rodents and insects)
there are a Lot of restrictions.

As for hand supports, you can do that too...but eh, it has to be all hands unfortunately, as if you use both hands and legs, it'll default to the legs.
Not difficult to do small creatures, just reduce the putty to as small as possible, there is a problem with this method though, i.e. other body pieces won't scale down nearly as small as the smallest putty size, so, you'd most likely end up with a ball with massive stilt legs, however, with clever use of body parts you can get something quite decent.
You are wholly correct on the symmetrical aspect though. However, you can add 'third' body parts by either placing a body part so close in between either two other symmetrical body parts so that is has no room to make it's other. Or do the same by clipping it in on itself. Either way you can delete the extra bits after. This however doesn't work well with limbs, as they tend to clip on themselves rather than become a single object.