After watching countless reviews and unboxings of shapeways puzzles, I've noticed how well they break in, making them turn so very smoothly. How well do you think a zhanchi would turn if it was 3D printed?

3D printed puzzles break in well because they start out very bad. You can get very reasonable turning but nothing close to what you can get from a commercial speed cube.

I really don't think it would be significantly worse than mass produced.
Here's why.
Will's Speed Pyraminx was 3D printed, and yet it turns amazing.
I think that with some Lubix and tensioning, a 3D printed Zhanchi would turn almost as well as a normal one.

-Doug

While I was able to get my pyraminx design to turn quite smoothly, it would be much smoother if it was injection molded. I'd imagine that polishing it would achieve similar results as well, but I doubt you'd see any improvements in 3d printing a mass produced puzzle design.

I thought about this when I first started designing in CAD (I'm still really new to it).

A more important concern would be the replicated design. I think it would be very difficult to achieve the same speed and turning results as an already mass produced Zhanchi. There are already different batches of Dayan 3x3's for example the really smooth 'original' zhanchi that had come from an early batch.

It would be interesting to find out... but also expensive.