Apparently this button is not attached to the camera in any way and will just fall out of the camera when you remove the bottom plate.

I recently got this film camera. It had a number of small issues, including this button being missing.

I quickly 3d modeled a replacement, I never saw the original part, but this works.

It will fit loosely in the hole of the bottom plate. but it is not rattling once the bottom plate is re-installed on the camera.

It does not poke out of the camera even when not depressed.

I suggest printing this in a durable plastic like ABS. I used eSun ABS+. Sliced at 0.1mm layer height. Print with a brim as the surface area of the first layer is very very small.