Hollow Core Keychain. DIY - Casting Aluminum at Home

I wanted to make some "unique" keychain. It'll have a hollow core and will consist of 2 parts.

Step 1: Casting

Making foam pattern, mold and start casting aluminum

Step 2: Processing

Grinding, drilling, threading, painting...

Step 3: The Bar Keychain Is Ready

The keychain is ready. It can be used to carry spare battery inside or maybe some other tiny things.