Size: Diameter: 34.6mm, Height(without thread stem): 15mm, Stem: 12mm

For smooth finish print with the head upside and change support overhang angle to more than 65 degrees so it wont mess with the threads and would supports only the plug's head like shown in the screenshot.

Also use brim for bed adhesion.

If you are using harder TPU you can play with infill with Cross 3D pattern to make it squishier. But mind that you may need to adjust the number of walls and top layers, so it would be more durable.

If you don't care for imperfections you can also print the plug with the head at the bottom, you will need less support that way.

If you plan to use the plug for stopping and etc. I would recommend to print it solid with say 1000 walls.