I wanted to use this longer hook 14.stl with puzzle part 8.stl.
I did not like tolerances, so i changed dimensions, now it fits tight, i had to tappy tap tap it.
( Source for tappy tap tap: https://www.youtube.com/watch?v=lZQ3wQjJwxw&feature=youtu.be&t=116 / 1:56-2:02 :)
If it is too tight with your printer / settings / liking, upscale it 1-3%.
I printed with 4 perimeters, 4/4 layers.
You may play with your settings.