Inspired by Marcel_X's design, but I wanted it to be firmly fixed (and also, I wanted to learn designing threads), so I created a version with a nut.

Printed in ABS. Note, threads are designed with no tolerances. I printed the bushing/flange part in 100%, and scaled the nut to 101.5% in X and Y (obviously not in Z, then the threads won't fit) and got a nice fit, both between the cooker / bushing and the bushing / nut. YMMV...
Used a 74mm hole saw.