Had no trouble at all printing these at .2mm. I have not setup the magnets yet, have them on order. Also used rubber bands in place of the silicone bands while i design bands made of NinjaFlex. Will post the NinjaFlex printable bands when i'm finished.
One question, however, When printed it appears that the 4-40 x 3/4" should maybe be qty 26, and possibly 6 1/4 or 1/2" 4-40 bolts for the grippers. Not sure if maybe i missed something in the instructable, but seems to me the lengths are incorrect. But still works just the same :)