Printed on my custom built BLV MGN Cube.
Print slowly and and make sure your retraction settings are perfect so you don't get strings jumping between islands -- strings will bind up the working parts.
Turn down your extrusion multiplier so you're just underextruding a tiny bit -- this will make sure that those gaps stay open.
This one popped right off the build plate fully free and working -- the tolerances (at least for my printer and filament) were just perfect.
Well worth the price. Now I'm going to go buy the other @clockworkspring gizmos. :-)