Posting this as requested by the knife creator uhltimate. This is a cover that goes over the handle of his knife to cover the spring! Here is a link to his knife https://makerworld.com/en/models/449279#profileId-356059
Instructions:
Lay the main assembled knife on top of this outer shell as shown in the photos
INSERT FLAT SIDE WITHOUT SWITCH FIRST (SHOWN IN 2nd and 3d pic) - THEN PRESS DOWN THE FRONT SWITCH SIDE (4th pic) BEFORE PRESSING DOWN THE BACK
Press firmly (takes some force) to push it inside and snap the cover over the knife for a tight snug fit!