This is my take on a gravity knife. 
I liked the idea and designs already out there, but I wanted a print in place Version, so I've designed one.

The v2 of the knife adds some details that where lacking in the first version. Now it looks a little bit sleeker in my opinion.

Print Instructions:

Rotate the knife by 90 degrees so th opening faces upwards (as seen in the picture) and use a raft. Infill and walls don't really matter all that much with this model. 

This is designed and meant to be used as a toy. Please don't modify it in any way, that could make it a weapon.