Note: This model was improved upon (to say the least) and successfully printed by user hannes04. He turned it into a system that I think could be very useful for printing structures. I have some additional improvements that I hope to test soon and upload, but in the mean time, try out my updated model and check out hannes04's system version as well. Let us both know what you think!
This joint is based off of photos from Instagram user "shino_bunny", which were brought to my attention in /r/woodworking on reddit.
The two pieces are identical and the very secure joint works in three separate configurations. The black piece is in the same position in all three examples, only the colored piece moves.
Modeled in Sketchup, untested.