This device is a singe / two-component, impact-based tool designed for cracking hard-shelled nuts using physical force transmitted via hand striking.

Components

Base Block (Receiver): 

A solid cuboid component featuring 3 carved recesses designed to securely hold a single nut (e.g., walnut, hazelnut).

Impact Block (Striker): 

A second solid cuboid component put directly over the Base Block, securing the nut in place

Preparation and Setup

Selection: Select a hard, stable, flat surface for operation. 

This is mandatory for transferring the necessary force.

Placement (Method A - Two-Piece Operation):

Place the Base Block onto the stable surface.
Insert a single nut into the carve-out of the Base Block, ensuring the nut is seated securely.
Place the Impact Block directly on top of the nut and Base Block, ensuring alignment.

Position your hand directly above the center of the Impact Block.
Deliver a single, sharp, downward strike with your fist onto the center of the Impact Block.
The force of the strike is transmitted through the Impact Block, compressing the nut against the Base Block, resulting in the controlled fracturing of the shell.

Placement (Method B - Surface-Assisted Operation):
Insert a single nut into the carve-out of the Base Block.
Flip the Base Block over so the nut faces the stable surface.
Place the nut/Base Block assembly onto the stable surface. 

Deliver a single, sharp, downward strike with your fist.
When using this method, the nut shell fractures against an open surface, which may cause shell fragments to eject laterally. 

Before striking, partially cup your non-striking hand over the edges of the Base Block to act as a debris shield. Maintain a clear line of sight.

May the force be with you….. 

The PLA prototype works well in most cases (used in the video) and is a fast print,

but I strongly suggest using the reinforced PETG Version V2.