Namedtuples are on way, if they don't have to be mutable:
from collections import namedtuple
MyTupleType = namedtuple('MyTupleType', ['field'])
yourobject = MyTupleType(field=3)
print(yourobject.field) # prints 3
If it's for testing, then using the Mock library is also handy (see http://www.voidspace.org.uk/python/mock/ ; unittest.mock
is part of the standard library since Python 3.3 as well).
yourobject = MagicMock()
yourobject.field = 3
Note that yourobject now has any field or method you try to access on it, and their values are all yet another MagicMock instance. It's a very powerful unit testing tool.
Lastly you can just create a boring dummy class:
class Dummy(object):
pass
yourobject = Dummy()
yourobject.field = 3