class User_Custom(Base):
    def __init__(self, ...):
        ...
        auth.settings.extra_fields['auth_user']= [
            Field('uuid', type='string', default = web2py_uuid(),
                        readable=False, writable=False, label=current.T('UUID')),
                ]

def create_user():
    dict__user = dict(
          first_name = random.choice(FIRST_NAMES),
          last_name = random.choice(LAST_NAMES),
          email = ...,
          password = ..,
          f_uuid = web2py_uuid(),
          )
    return db.auth_user.insert(**dict__user)

def create_profile(count = 100):
    for idx in range(count):
        user_id = create_user()
        # create a bunch of data for tables referenced by db.auth_user