I had an electrical box at work that had an odd size knockout hole. Made this to fit and be weather tight. Fits smaller than 1/2" knockout and up to 3/4" knockout. Printed washer from TPU with thicker side walls and 30 percent infill. The main parts I printed in ABS. 50 percent infill, 6 layer walls for rigidity of thread shaft. Do not overtighten. Hand tight is plenty to keep out weather and rodents / insects.