valorant karambit prime retractable

I need you to design the functional valorant karambit prime 2.0 3d modeling (with the same video game animation) guide link. the file is already done, only the back part should be modified so that it is exact.
https://www.thingiverse.com/thing:5240649/files this link is the one of the file already made
https://youtu.be/Hwc17n9R2a8 here is how they should polish it