I happened to just ask this question to the marketing person at RethinkDB and she says: "Hey Will, we use Canary Marketing now (who are absolutely amazing..
hands down some of the best swag vendors I’ve ever come across and I
used to do this for a living lol) stu@canarymarketing.com
[11:09]
We print on American Apparel 50/50 or Belle + Canvas tri-blend
[11:09]
We used to use local printers, but Canary is best."