I saw my nephew playing with something similar. I modeled a larger one for my kids to play with. This one is 5x5x5mm for all the square aspects with the exception of the center hole. It's 5.1x5.1mm for obvious reasons. I'd suggest you only print two and test out the interlock. Due to different printers, nozzles, calibration variation, etc., this toy may not work as designed on some printers without modification. If you need a revision, let me know and I'll be glad to modify it for you. This one printed just fine on my MP-select mini on the first go with the settings from the demo gcode file. Happy printing.