You have to print part 1 and part 3 twice.
I just took some pictures of this video: 

Loaded them in onshape and voilà.
Haven't printed them myself but should work fine in TPU.
 

Link to onshape:
https://cad.onshape.com/documents/a9b03a72594fb3fecbfebf2f/w/4da05f6acf6cc2093b3cac7f/e/0e20bca0d7172fa10f97ce01

 counter-snap