I wrote peewee, a single file Python ORM. It's codebase is very small but it is extremely capable.
I'm quite impressed with how easy to use everything is, despite having used pwiz to generate my model classes. I had to manually edit a couple of the "related_name" fields for some foreign keys that are common between tables, as well as import the ArrayField type from playhouse.postgres_ext, but otherwise had a very, very easy time getting everything set up for what I wanted.
Thanks again for this, I didn't think porting my database schema over to Python would be so easy.
Nowadays though I tend to use either Key/Value stores or straight SQL.