This model is designed by dma81 (http://bit.ly/2Iwy8it), thank you very much for your great support. For details, please see the description below:
Designed in Tinkercad to avoid bruising my fingers while leveling the print bed :).
It's a tight fit for 11mm metal screws, but they work great.
Printer: Anycubic Prusa I3
Notes: Printed in PETG