Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4806549.
Air Filter Cover Knob for Briggs and Stratton by RebelTaz
This is a common style air filter on several Briggs and Stratton engine models. From what I have found, it can replace part numbers 844618 / 691985 / 491875 and probably others. For this, you will need a 7/16 hex nut with the proper threads to match your stud. Simply print the parts in the orientation given, drop your nut into the knob and press the plug in above the nut, with the beveled end down. This locks the nut in place and give the knob a more finished look.
For strength, I recommend 1.6mm walls with 40% triangular infill.
NOTE Due to either a Thingiverse bug or (more likely) shadowbanning, my models no longer show up under the [Newest] listings. If you want to see more of my models, please be sure to 'follow' me. If you print this, it would really help if you'd post a 'make' so that others could find this model.