USE AT YOUR OWN RISK!  I do not claim that use of this part is safe or smart!

This is intended as a replacement for the mulch plug in a Kobalt corded electric lawnmower (13-amp, 21-inch, model KM 211-06).

The part isn't a 100% perfect fit, but it fits “close enough” to prevent nearly all of the grass clippings from flying out of the rear of the mower.  The part pictured is from an earlier version.  The posted version has a slightly wider rear to eliminate the small gap along the right side (as seen in the second to last picture and the video).

To install the part, you have to put it in at a slight angle so that the right side of the plug goes in first.  The triangular grip on the rear should point up.

Prior to printing, you may need to rotate the part so that the flat bottom is on the build plate.  In this orientation, supports should not be needed.

I printed it in PLA+ using a 0.6 mm nozzle, 1.2 mm walls, 10% gyroid infill, no skirt, and no supports.  However, I'm thinking of trying a semi-rigid TPU (98A durometer) for better impact resistance and toughness.