Obviously, it is a unforgivable sin to print this in anything other than “the iconic red shutter button”-red, or spray painting it afterwards, like i did.

There a three versions with different tolerances. “smaller” is 0.2mm smaller in x/y direction, while “even smaller” is 0.3mm smaller. It's best to print all versions at the same time and try the fit, as they print very fast, anyway. If you are spray painting them, print a set of two to account for the inevitable loss of the small parts flying away while spraying them.

The part is modeled after the original, with the same lower structure that activates the button. Print it with the flat part that is pressed later in use, facing down to get a smooth print. If you need any adjustments, see the provided .scad file (messy!)