worked out - wsf surprisingly more beautiful for this one than grey robust, but all operate with 1/4" ball Also, more a labyrinth than a maze.

Steel. This one arrived a bit tight.. Opened very slightly and works nicely

Steel. Ball very free, but caged. Fun.

Too thin to print in stainless (2mm). Expanded manually.

Yep, good. WSF is aces for this. 1/4" balls works nicely. Guess more a labyrinth rather than maze.

Grey robust.

Steel. Ball arrived a little bound. Broke it free, but still somewhat tight. Maybe I push the limits of precision. Popped it out and replaced with ...

Steel. Ball a bit tight. Popped out and replaced with 1/4" bronze ball.

Steel. Ball tight, but runs freely.

Steel. Ball tight tolerance, but runs freely