I downloaded a couple I found online. They were all too big. I tried scaling them but it became clear that the plastic post requirement of 1mm was not going to be strong or render well. Then I realized that maybe this model was different. The kickstand was gone, but there was a 1mm diameter steel post about 13mm long left behind.
This kickstand needs a metal post insert. You could probably make one from a needle or pin it is so small. I also added the notches back to the side so it clicks into place in the case.
This will print about 10mm wide and 38mm long.
I printed it in PETG on its side to give strength when jamming the post into place.
I printed this with a .4mm nozzle and .15mm layer. The tolerance may be too much for some. You get that one layer around the hinge.
I might be .2mm or so too thick, but it works.
The author hasn't provided the model origin yet.