Eunuchs Splinter... no balls.  The maze is negotiated by pins in the box top... You guide the pins through the maze (mirrored on opposite sides) to close/open the box.
Any ball bearing would only finish up on the floor and any parent knows the torture of Legos on the floor... ball bearing not only hurt but send one on their arse.

If your first cut is too short... Take the second cut from the longer end... LBD