Printing bed calibration nut

I wasn't happy with the available printing bed accessories so I created my own.

The center contains a M3 thread to screw unto the printing bed leveling rods.

Close to 7 cm (2.8 inches) printed provides good grip while (un)tightening and the spokes give some feedback on how much you've rotated the piece.

This is my first openscad project. I am looking for feedback. If you have any comments, hints or suggestions let me know.