Flash90

class Chel(models.Model):
    name = models.CharField(max_length=10)
guy = Chel(name='xxx')

class Meta(type):
    def __call__(self, *args, **kwargs):
        obj = type.__call__(self, *args)
        for name in kwargs:
            setattr(obj, name, kwargs[name])
        return obj

class A(object):
    __metaclass__ = Meta

a = A(x=1)
TypeError: object() takes no parameters
a = A()(x=1)
TypeError: 'A' object is not callable

A = type.__new__(Meta, 'A', (object,), {})
#и теперь при создании экземпляров можно определять атрибуты:
a1 = A(attr1=1, attr2="test")
print(a1.attr1, a1.attr2) 
1    test