It looks nice. Printed easily. No idea how it fits with Duplo yet.
I have discovered 2 things:
(1) TEVO Tarantula has really unreliable Z positioning (springy), so my tweak of adding 0.1mm to the height should probably not have been done since the bricks print consistently 0.1mm higher than real blocks on my Anycubic delta...
(2) Getting the extruder calibration just right REALLY matters for these bricks. Any over extrusion results in studs that are too wide and the internal cylinder is also too thick, so they won't even fit with each other. Under extrusion has resulted in studs that break off.
I gave it to a colleague and he says it fits perfectly!
He bought a printer immediately xD