My microwave was wobbly on the IKEA OMAR so I made this simple clip to set it in place.

Print in the orientation the stl is in. I had to pinch the wires of the OMAR together a bit to get it to snap in place, but it is a solid fit.

Make sure to measure your Microwave feet, the hole should be 20mm. You may need to resize so I included the CAD files.