I've seen an interesting design of a meat hammer which looks like a knuckle-duster and decided to make one.
Step 1: Cutting Polystyrene
First step is to cut a pattern of a knuckle-duster using a polystyrene.
Step 2: Making a Mold
During the next step a mold should be made.
Step 3: Casting Aluminum
When aluminum is melted it's time to pour aluminum into the mold.
Step 4: Open the Mold
After opening the mold I don't see a lot of issues. Knuckle-duster looks not bad.
Step 5: Final Process
After sanding the knuckle-duster is finished. Very comfortable to use as a kitchen tool for meat tenderizing.