Did you purchase a Slice Auto Retract Utility Knife, only to be surprised at the lack of a latch? Fear no more. Print this on its side with supports. Break off the supports. Slide the fat wide part in. Rotate and slide the rest back. You can still operate as an "auto". Or push the part you just printed with the lever and it will lock into place. Best of both worlds.

Creality

Ender 3

Yes

Yes

.35mm

Doesn't matter

.4mm nozzle. .3 layer height.